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Is it theoretically possible to create two humans by splitting one human in two?

Is it theoretically possible to create two humans by splitting one human in two?


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There have been cases where a person has had one of their brain hemispheres removed, and they ended up living a fairly normal life. Could it be possible to split a normal person down the middle and create two people, each with a brain hemisphere? Machines could be used to replace organs that can't be split, like the heart.

I'm assuming there would exist some very advanced technology to prevent excessive blood loss and other problems with splitting a person down the middle.


If you split a human early enough (in the first weeks after fertilization), you can get monozygotic twins.

Other than that, you are in the field of science fiction and we cannot safely answer such question on a science website. I am not sure your question will be accepted in its current format but you may try WorldBuilding.SE.

And if you like fantasy novels, I recommend The Cloven Viscount by Italo Calving! You will definitely not learn much about biology in this book though.


Given how some parts of the brain control the opposite hemisphere of the body, and how this is not consistent throughout the entire brain, you would have to do a lot more than split someone in half down the middle.

Importantly, in split-brain patients only the cerebral cortex is hemisected, and only at a particular (though significant) point of connection, called the corpus callosum. It would not be possible to do this through the entire brain.

Especially in adult humans, some functions become lateralized, as well, so each "person" would be capable of different functions.


Why do you have two lungs but only one heart?

Your body is pretty amazing. At any given point you have a great many biological processes going on, such as digestion, respiration, metabolism, and fighting off invading bacteria. Different regions and systems within your body work together to create a state of balance -- just the right amount of blood sugar here, just enough electrolytes there -- to keep you working at peak performance.

But have you ever asked yourself how your body got to be the way it is? Why do you have two of some organs and just one of others? Take the heart and lungs, for instance -- why do you have two lungs but just one heart? Wouldn't it be better to have two hearts?

Your vital organs -- like your lungs, your heart, your pancreas, brain and liver -- are just that, vital. Not only are they vital to life, they are also vital to one another. Your lungs, for example, breathe in oxygen and exhale carbon dioxide (one of your body's waste products). The lungs transfer oxygen to the blood, which is carried to the heart for distribution throughout the rest of the body. The blood carries waste carbon dioxide back to the lungs, where it is absorbed and exhaled. It's a beautiful system. But how did it come about?

It's a very ancient system, says Rutgers University anthropologist Susan Cachel -- and it's not unique to humans. The organ systems we find in most animals contain one heart and two lungs. That is, with the exception of earthworms and cephalopods -- the invertebrate class which includes octopi and squid. Earthworms have five heart-like structures. Cephalopods have three hearts (two to send blood to the gills, and one to send blood to the rest of the body) and no lungs.

Cachel says that the one heart/two lungs system began to emerge about 300 million years ago, when animals first moved from sea to land to escape predators and find new sources of food. From that point on, it's been the norm. But why didn't it continue to change?

In this case, Occam's razor provides the key -- the simplest explanation is usually the right one. Ultimately most animals developed a system of two lungs and one heart (along with the rest of their organs) because that's what was needed to survive and thrive on Earth. People didn't develop two hearts or eight legs or wings because we didn't need them for survival. And we developed two lungs because we need them.

Phylogeny is the study of how the first ribonucleic acid (RNA) strands in Earth's primordial soup developed into humans and other animals. As these animals evolved into such divergent species as birds, insects and humans, the organ systems in those animals remained similar to one another. We still have stomachs to digest food, lungs to breathe air, and kidneys to filter waste. All of this indicates that species -- including humans -- have been shaped and molded specifically to live on Earth.

So does this mean that our system of internal organs is perfect? We know through our study of disease that going from two lungs to one is detrimental to our health, but what about adding an extra heart? Wouldn't that make us better able to survive? Read the next page to find out about what it would be like to have two hearts.

You might imagine that having two of some organs is redundant. We have two lungs, two kidneys, two eyes -- each doing the same job at the same time. But Dr. Tony Neff, a professor of anatomy and cell biology at Indiana University - Bloomington, warns against downplaying the role of duplicate organs. It takes both organs in those sets to carry out their job fully Although one can function alone, the process it carries out will not be done at full capacity, and the rest of the body suffers. For example, you can see with only one eye, but the eyes' function of providing depth perception will suffer and you'll bump into things much more frequently seeing with one eye than you would with two.

So if you need both lungs to function at full capacity, what would happen if you had an extra heart? Would the performance of the processes it carries out double?

Not at first, says physiologist Bruce Martin, a colleague of Dr. Neff's at Indiana University. Your body is a system, and it's built so that the system is always functioning at its full capacity. When the system is attacked -- for example, through starvation -- all parts of the system suffer at the same rate. Conversely, when one part breaks down, the whole system suffers. If your lungs become irreparably damaged -- say, through emphysema -- the rest of the system will slow down to accommodate the broken part.

So since your system is already functioning at full bore, the addition of an extra heart wouldn't do much. But your system also possesses potential function, as seen in the muscles, when they're called upon to act beyond their normal capacity, like in the case of hysterical strength. We can train our bodies to function at higher levels, like athletes do. Since the heart pumps blood to the muscles, with a second heart your muscles would eventually grow stronger with time. Once the rest of the system is used to having a second heart, a person could grow stronger and have more endurance [source: Martin].

But the same can't be said for your brain. The brain is already getting more than enough blood to it, so it wouldn't function at a higher level, theorizes Dr. Martin.

Interestingly, when we are in the embryonic stage of development, we actually do have two hearts. The heart primordia (which describes the stage of the heart's development) in the embryonic stage is actually two hearts, which eventually fuse together into one heart with four chambers. Embryologists in the 1920s and '30s kept the heart primordia from fusing in embryonic frogs, and the frogs that grew up developed two hearts. The same also goes for our eyes. We begin with one primordia of the eye, which eventually separates to form two. If the primordia is kept from splitting, one central eye develops, like a cyclops, says Dr. Neff.

So it's theoretically possible for us to develop two hearts. And if we could determine how to use both fully, we could also advance ourselves into a species of super-strong, intellectually average beings. But wouldn't tampering with our own evolution as a species be dangerous?

"We've already taken ourselves out of evolution," says Rutgers' Susan Cachel. "[Humans are] all effectively tropical animals, and through our use of technology, like winter clothes, we've shielded ourselves from the effects of cold weather."

So we've beaten natural selection by the elements. We'll see what we can achieve with two hearts.

For more information on physiology, evolution and related topics read the next page.


Could Humans Be Cloned?

The news that researchers have used cloning to make human embryos for the purpose of producing stem cells may have some people wondering if it would ever be possible to clone a person.

Although it would be unethical, experts say it is likely biologically possible to clone a human being. But even putting ethics aside, the sheer amount of resources needed to do it is a significant barrier.

Since the 1950s when researchers cloned a frog, scientists have cloned dozens of animal species, including mice, cats, sheep, pigs and cows.

In each case, researchers encountered problems that needed to be overcome with trial and error, said Dr. Robert Lanza, chief scientific officer at the biotech company Advanced Cell Technology, which works on cell therapies for human diseases, and has cloned animals.

With mice, researchers were able to use thousands of eggs, and conduct many experiments, to work out these problems, Lanza said. "It&rsquos a numbers game," he said.

But with primates, eggs are a very precious resource, and it is not easy to acquire them to conduct experiments, Lanza said.

In addition, researchers can't simply apply what they've learned from cloning mice or cows to cloning people.

For instance, cloning an animal requires that researchers first remove the nucleus of an egg cell. When researchers do this, they also remove proteins that are essential to help cells divide, Lanza said. In mice, this isn't a problem, because the embryo that is ultimately created is able to make these proteins again. But primates aren't able to do this, and researchers think it may be one reason that attempts to clone monkeys have failed, Lanza said. [See How Stem Cell Cloning Works (Infographic)]

What's more, cloned animals often have different kinds of genetic abnormalities that can prevent embryo implantation in a uterus, or cause the fetus to spontaneously abort, or the animal to die shortly after birth, Lanza said.

These abnormities are common because cloned embryos have just one parent rather than two, which means that a molecular process known as "imprinting" does not occur properly in cloned embryos, Lanza said. Imprinting takes place during embryo development, and selectively silences certain genes from one parent or the other.

Problems with imprinting can result in extremely large placentas, which ultimately leads to problems with blood flow for the fetus, Lanza said. In one experiment, Lanza and colleagues cloned a species of cattle called banteng, and it was born at twice the size of a normal banteng. It had to be euthanized, Lanza said.

The extremely high rate of death, and the risk of developmental abnormities from cloning makes cloning people unethical, Lanza said.

"It's like sending your baby up in a rocket knowing there's a 50-50 chance it's going to blow up. It's grossly unethical," Lanza said.


How else would a two headed human differ from us? [closed]

Want to improve this question? Update the question so it's on-topic for Worldbuilding Stack Exchange.

Due to *cough* hmrnrnrmrn rmrmr *cough*, some humans are born with two heads. This has been happening for at least as long as humans have been making cave paintings and it seems to be nothing to worry about (unless you don't get along with your bodymate, in which case you should contact a trained psychologist and refrain from fighting or biting yourself until an appointment is available).

They have two heads (no connection between the brains), a Y-shaped oesophagus and wind-pipe, a slightly larger chest to contain their marginally larger heart, lungs, veins and arteries to handle their increased oxygen requirements and (anecdotally at least) a tremendous appetite. However, as they could not be proven to be anything other than than human, further testing and experimentation hasn't been legally or ethically possible.

What other, if any, biological differences would two-headed humans show in order to operate just as efficiently and easily as single-headed humans?

--EDIT--
(From comment by OP)
@MontyWild Most of them can't tell because they generally don't disagree and coordinating movement becomes subconscious, but those that do fight claim they are both in control and that being shouted at and punched by yourself is too distracting to concentrate on which head is doing what


The birth of half-human, half-animal chimeras

In H. G. Wells's The Island of Doctor Moreau, the shipwrecked hero Edward Pendrick is walking through a forest glade when he chances upon a group of two men and a woman squatting around a fallen tree. They are naked apart from a few rags tied around their waist, with "fat, heavy, chinless faces, retreating foreheads, and a scant bristly hair upon their foreheads." Pendrick notes that "I never saw such bestial looking creatures."

As Pendrick approaches, they attempt to talk to him, but their speech is "thick and slopping" and their heads sway as they speak, "reciting some complicated gibberish". Despite their clothes and their appearance, he perceives the "irresistible suggestion of a hog, a swinish taint" in their manner. They are, he concludes, "grotesque travesties of men".

Wandering into Doctor Moreau's operating room one night, Pendrick eventually uncovers the truth: his host has been transforming beasts into humans, sculpting their bodies and their brains into his own image. But despite his best efforts he can never eliminate their most basic instincts, and the fragile society soon regresses to dangerous anarchy, leading to Moreau's death.

It is 120 years since Wells first published his novel, and to read some recent headlines you would think that we are veering dangerously close to his dystopic vision. "Frankenstein scientists developing part-human part-animal chimera," exclaimed the UK's Daily Mirror in May 2016. "Science wants to break down the fence between man and beast," the Washington Times declared two months later, fearing that sentient animals would soon be unleashed on the world.

The hope is to implant human stem cells in an animal embryo so that it will grow specific human organs. The approach could, in theory, provide a ready-made replacement for a diseased heart or liver &ndash eliminating the wait for a human donor and reducing the risk of organ rejection.

It's going to open up a new understanding of biology

These bold and controversial plans are the culmination of more than three decades of research. These experiments have helped us understand some of the biggest mysteries of life, delineate the boundaries between species, and explore how a ragbag bunch of cells in the womb coalesce and grow into a living, breathing being.

With new plans to fund the projects, we are now reaching a critical point in this research. "Things are moving very fast in this field today," says Janet Rossant at the Hospital for Sick Children in Toronto, and one of the early pioneers of chimera research. "It's going to open up a new understanding of biology."

That is, provided we can resolve some knotty ethical issues first &ndash questions that may permanently change our understanding of what it means to be human.

For millennia, chimeras were literally the stuff of legend. The term comes from Greek mythology, with Homer describing a strange hybrid "of immortal make, not human, lion-fronted and snake behind, a goat in the middle". It was said to breathe fire as it roamed Lycia in Asia Minor.

At least 8% of non-identical twins have absorbed cells from their brother or sister

In reality, chimeras in science are less impressive. The word describes any creature containing a fusion of genetically-distinct tissues. This can occur naturally, if twin embryos fuse soon after conception, with striking results.

Consider the "bilateral gynandromorphs", in which one side of the body is male, the other female. These animals are essentially two non-identical twins joined down the centre. If the two sexes have wildly different markings &ndash as is the case for many birds and insects &ndash this can lead to a bizarre appearance, such as a northern cardinal that had grown bright red plumage on half of its body, while the rest was grey.

Most often, however, the cells mix to form a subtler mosaic across the whole body, and chimeras look and act like other individuals within the species. There is even a chance that you are one yourself. Studies suggest that at least 8% of non-identical twins have absorbed cells from their brother or sister.

The mixed bag of animals from Greek legends certainly cannot be found in nature. But this has not stopped scientists from trying to create their own hybrid chimeras in the lab.

Janet Rossant, then at Brock University, Canada, was one of the first to succeed. In 1980, she published a paper in the journal Science announcing a chimera that combined two mice species: an albino laboratory mouse (Mus musculus) and a Ryukyu mouse (Mus caroli), a wild species from east Asia.

Previous attempts to produce a hybrid "interspecific" chimera often ended in disappointment. The embryos simply failed to embed in the uterus, and those that did were deformed and stunted, and typically miscarried before they reached term.

We showed you really could cross species boundaries

Rossant's technique involved a delicate operation at a critical point in pregnancy, around four days after mating. At this point, the fertilised egg has divided into a small bundle of cells known as the blastocyst. This contains an inner cell mass, surrounded by a protective outer layer called the trophoblast, which goes on to form the placenta.

Working with William Frels, Rossant took the M. musculus and injected it with the inner cell mass of the other species, M. caroli. They then implanted this mixed bag of cells back into the M. musculus mothers. By ensuring that the M. musculus trophoblast remained intact, they ensured that the resulting placenta would match the mother's DNA. This helped the embryo embed in the uterus. Next they sat back and waited 18 days for the pregnancies to unfold.

It was a resounding success of the 48 resulting offspring, 38 were a blend of tissues from both species. "We showed you really could cross species boundaries," Rossant says. The blend was apparent in the mice's coats, with alternating patches of albino white from the M. musculus and the tawny stripes of the M. caroli.

Even their temperaments were noticeably different from their parents. "It was quite obviously a weird mixture," says Rossant. "M. caroli are very jumpy: you would need to put them at the bottom of a garbage can so they don't jump out at you, and you'd handle them with forceps and leather gloves." The M. musculus were much calmer. "The chimeras were somewhat in between."

With today's understanding of neuroscience, Rossant thinks this could help us to explore the reasons why different species act the way they do. "You could map the behavioural differences against the different regions of the brain that were occupied by the two species," she says. "I think that could be very interesting to examine."

Time magazine described the geep as "a zookeeper's prank: a goat dressed in a sweater of angora"

In her early work Rossant used these chimeras to probe our basic biology. Back when genetic screening was in its infancy, the marked differences between the two species helped to identify the spread of cells within the body, allowing biologists to examine which elements of the early embryo go on to create the different organs.

The two lineages could even help scientists investigate the role of certain genes. They could create a mutation in one of the original embryos, but not the other. Watching the effect on the resulting chimera could then help tease apart a gene's many functions across different parts of the body.

Using Rossant's technique, a handful of other hybrid chimeras soon emerged kicking and mewling in labs across the world. They included a goat-sheep chimera, dubbed a geep. The animal was striking to see, a patchwork of wool and coarse hair. Time described it as "a zookeeper's prank: a goat dressed in a sweater of angora."

Rossant also advised various conservation projects, which hoped to use her technique to implant embryos of endangered species into the wombs of domestic animals. "I'm not sure that has ever entirely worked, but the concept is still there."

Now the aim is to add humans to the mix, in a project that could herald a new era of "regenerative medicine".

For two decades, doctors have tried to find ways to harvest stem cells, which have the potential to form any kind of tissue, and nudge them to regrow new organs in a petri dish. The strategy would have enormous potential for replacing diseased organs.

The aim is to create chimera animals that can grow organs to order

"The only problem is that, although these are very similar to the cells in the embryo, they are not identical," says Juan Carlos Izpisua Belmonte at the Salk Institute for Biological Studies in La Jolla, California. So far, none have been fit for transplantation.

Izpisua Belmonte, and a handful of others like him, think the answer is lurking in the farmyard. The aim is to create chimera animals that can grow organs to order. "Embryogenesis happens every day and the embryo comes out perfect 99% of the time," says Izpisua Belmonte. "We don't know how to do this in vitro, but an animal does it very well, so why not let nature do the heavy lifting?"

Today's plans to build a human-animal chimera may have provoked controversy, but they are nothing compared to the scandalous experiments of Ilia Ivanov, also known as the "Red Frankenstein". Hoping to prove our close evolutionary ties to other primates once and for all, Ivanov hatched a crackpot scheme to breed a human-ape hybrid.

Starting in the mid-1920s, he tried to inseminate chimps with human sperm, and even tried to transplant a woman's ovary into a chimp called Nora, but she died before she could conceive.

When all else failed, he gathered five Soviet women who were willing to carry the hybrid. However, the prospective father &ndash called Tarzan &ndash died of a brain haemorrhage before he could carry out his plan. Ivanov was eventually arrested and exiled to Kazakhstan in 1930 for supporting the "international bourgeoisie" a crime that had nothing to do with his grotesque experiments.

Unlike the "geep", which showed a mosaic of tissue across its body, the foreign tissue in these chimeras would be limited to a specific organ. By manipulating certain genes, the researchers hope they could knock out the target organ in the host, creating a void for the human cells to colonise and grow to the required size and shape. "The animal is an incubator," says Pablo Juan Ross at the University of California-Davis, who is also investigating the possibility.

We already know that it is theoretically possible. In 2010 Hiromitsu Nakauchi of Stanford University School of Medicine and his colleagues created a rat pancreas in a mouse body using a similar technique. Pigs are currently the preferred host, as they are anatomically remarkably similar to humans.

If it succeeds, the strategy would solve many of the problems with organ donation today.

"The average waiting time for a kidney is three years," explains Ross. In contrast, a custom-made organ grown in a pig would be ready in as little as five months. "That's another advantage of using pigs. They grow very quickly."

In 2015, the US National Institutes of Health announced a moratorium on funding for human-animal chimera

Beyond transplantation, a human-animal chimera could also transform the way we hunt for drugs.

Currently, many new treatments may appear to be effective in animal trials, but have unexpected effects in humans. "All that money and time gets lost," says Izpisua Belmonte.

Consider a new drug for liver disease, say. "If we were able to put human cells inside a pig's liver, then within the first year of developing the compound, we could see if it was toxic for humans," he says.

Rossant agrees that the approach has great potential, although these are the first steps on a very long road. "I have to admire their bravery in taking this on," she says. "It's doable but I must say there are very serious challenges."

Many of these difficulties are technical.

The evolutionary gap between humans and pigs is far greater than the distance between a rat and a mouse, and scientists know from experience that this makes it harder for the donor cells to take root. "You need to create the conditions so that the human cells can survive and thrive," says Izpisua Belmonte. This will involve finding the pristine source of human stem cells capable of transforming into any tissue, and perhaps genetically modifying the host to make it more hospitable.

It would be truly horrific to create a human mind trapped in an animal's body

But it is the ethical concerns that have so far stalled research. In 2015, the US National Institutes of Health announced a moratorium on funding for human-animal chimera. It has since announced plans to lift that ban, provided that each experiment undergoes an extra review before funding is approved. In the meantime, Izpisua Belmonte has been offered a $2.5m (£2m) grant on the condition that he uses monkey, rather than human, stem cells to create the chimera.

A particularly emotive concern is that the stem cells will reach the pig's brain, creating an animal that shares some of our behaviours and abilities. "I do think that has to be something that is taken into account and discussed extensively," says Rossant. After all, she found that her chimeras shared the temperaments of both species. It would be truly horrific to create a human mind trapped in an animal's body, a nightmare fit for Wells.

The researchers point to some possible precautions. "By injecting the cells in a particular stage of embryo development, we might be able to avoid that happening," says Izpisua Belmonte. Another option may be to program the stem cells with "suicide genes" that would cause them to self-destruct in certain conditions, to prevent them from embedding in neural tissue.

Even so, these solutions have not convinced Stuart Newman, a cell biologist at New York Medical College, US. He says he has been worried about the direction of this research ever since the creation of the geep in the 1980s. His concern is not so much about the plans today, but a future where the chimera steadily take on more human characteristics.

"These things become more interesting, scientifically and medically, the more human they are," says Newman. "So you might say now that 'I would never make something mostly human', but there is an impulse to do it. There's a kind of momentum to the whole enterprise that makes you want to go further and further."

How we talk about humans during this debate may inadvertently change how we look at ourselves

Suppose that scientists created a chimera to study a new treatment for Alzheimer's. A team of researchers may start out with permission to create a chimera that has a 20% human brain, say, only to decide that 30% or 40% would be necessary to properly understand the effects of a new drug. Scientific funding bodies often require more and more ambitious targets, Newman says. "It's not that people are aspiring to create abominations&hellip but things just keep going, there's no natural stopping point."

Just as importantly, he thinks that it will numb our sense of our own humanity. "There's the transformation of our culture that allows us to cross these boundaries. It plays on the idea of the human as just another material object," he says. For instance, if human chimera exist, we may not be so worried about manipulating our own genes to create designer babies.

Newman is not alone in these views.

John Evans, a sociologist at the University of California San Diego, US, points out that the very discussion of human-animal chimera focusses on their cognitive capacities.

For instance, we might decide that it is okay to treat them in one way as long as they lack human rationality or language, but that train of logic could lead us down a slippery slope when considering other people within our own species. "If the public thinks that a human is a compilation of capacities, those existing humans with fewer of these valued capacities will be considered to be of lesser value," Evans writes.

Our gut reactions should not shape the moral discussion

For his part, Izpisua Belmonte thinks that many of these concerns &ndash particularly the more sensational headlines &ndash are premature. "The media and the regulators think that we are going to get important human organs growing inside a pig tomorrow," he says. "That's science fiction. We are at the earliest stage."

And as an editorial in the journal Nature argued, perhaps our gut reactions should not shape the moral discussion. The idea of a chimera may be disgusting to some, but the suffering of people with untreatable illnesses is equally horrendous. Our decisions need to be based on more than just our initial reactions.

Whatever conclusions we reach, we need to be aware that the repercussions could stretch far beyond the science at hand. "How we talk about humans during this debate may inadvertently change how we look at ourselves," writes Evans.

The question of what defines our humanity was, after all, at the heart of Wells' classic novel. Once Pendrick has escaped the island of Doctor Moreau, he returns to a life of solitude in the English countryside, preferring to spend the lonely nights watching the heavens.

Having witnessed the boundary between species broken so violently, he cannot meet another human being without seeing the beast inside us all. "It seemed that I too was not a reasonable creature, but only an animal tormented with some strange disorder in its brain which sent it to wander alone, like a sheep stricken with gid."

David Robson is BBC Future&rsquos feature writer. He is @d_a_robson on Twitter.


Conflict as Paradigm

The primary motivation for most work on human–wildlife conflict has been protecting threatened wildlife from anthropogenic threats. These efforts have aimed to reduce the impacts on wildlife and habitats, mitigate negative impacts of wildlife, and persuade and assist locals to adapt to living alongside damage-causing wildlife (Pooley et al. 2017 ). The focus has been on negative impacts of humans on wildlife and vice versa.

In their survey of the scientific literature on human–wildlife relations, Bhatia et al. ( 2019 ) found that 71% of 250 papers focused on human–wildlife conflict, 2% focused on coexistence, and 8% focused on neutral interactions. Although this study is based on a keyword search rather than the concept, the focus on conflict in the literature on human–wildlife interactions is indisputably overwhelming (König et al. 2020 ).

This framing positions wild animals as consciously combative with humans and reinforces a human–nature dichotomy framed as oppositional (Peterson et al. 2010 ). Recent thinking is more nuanced, however. For example, Bruskotter et al. ( 2015 ) conceptualize of a continuum of behaviors from intolerance to stewardship. Frank et al. ( 2019 ) propose a continuum of human responses to wildlife from conflicts to coexistence, urging researchers to consider positive as well as negative interactions. Bhatia et al. ( 2019 ) take a similar line, adding a typology of responses with the aim of better understanding the myriad factors influencing responses to wildlife. Although only 1% of surveyed papers evoked coexistence and conflict (Bhatia et al. 2019 ), and case studies are scarce, presumably in places where wildlife (e.g., African megafauna or rich birdlife in Indian farmlands) has survived outside protected areas both coexistence and conflicts have been present a long time.

Although Frank et al. ( 2019 ) are fully aware of the multidimensional and dynamic nature of human–wildlife interactions, their continuum framework can be interpreted as suggesting conflict and coexistence occupy opposite poles of a linear continuum. However, coexistence does not presume the absence of conflict. Conflict is a part of life, and can be a catalyst for positive change (Madden & McQuinn 2015 ). Another potential pitfall of the continuum concept is that as it is much easier to count direct, negative impacts than instances of coexistence, research in this shared dimension is skewed towards conflict. Counting the hits and not the misses similarly bedevils quantitative attempts to assess human–wildlife relations (Powell et al., 2020 ).


Are Human-Chimp Hybrids Possible?

Wow, that's interesting, thanks for sharing. I was happy to learn this kind of interbreeding is probably not realistic. It does make you wonder what may be possible in the future.

Not to mention that its nearly impossible to find a date movie that chimps & humans both enjoy.

Humans and chimps have DNA that is something close to 99% identical,

Please, get a hold of some more accurate, up-to-date information.

Genome and gene alterations by insertions and deletions in the evolution of human and chimpanzee chromosome 22Natalia Volfovsky, Taras K Oleksyk, Kristine C Cruz, Ann L Truelove, Robert M Stephens and Michael W SmithBMC Genomics 2009, 10:51doi:10.1186/1471-2164-10-51Published: 26 January 2009

. Initially, differences between humans and chimpanzees were estimated at 1% [7, 17, 18], but later this number was refined to 1.2% [8]. Several studies pointed out that the number of differences is much higher when indels (insertions and deletions) are included in the comparison [19-21], and the total divergence may be as high as 6.5% [19]. Removing repeats and low-complexity DNA reduces this calculation to 2.4% [19], doubling the original estimates.

BTW, when indels are accounted for, differences between one Homo sapiens individual and another may as much as 1% - 3%.

This tells us the variation between two groups - human and chimpanzees. But what's the variation within each group? Presumably it's fractions of 1%.

I think humans have already screwed up this species and the likelihood of their survival in natural habitats.

Would a female chimpanzee want to have a weird, half-human baby that would be taken away from her, raised and tested ad nauseam in a lab situation? I don't think so.

Interesting! Thanks for the video.

So . who else read Next by Michael Crichton?

But what's the variation within each group?

Two human individuals will differ in their DNA by 1-3%, or so says Craig Venter.

That's nice to know how much of our DNA we have in common, but don't forget to add that in terms of the number of chromosomes, humans have 46 but chimpanzees have 48. Trying to make a hybrid would result in an unmatched chromosome. There are enough HUMANS with significant medical problems because they do not have the proper number of chromosomes. It is likely that a cross-bred embryo would not be viable.

I wish you people wouldn't be so negative. Maybe it won't work, but we'll never know unless we try, right? And I, for one, would love having a chuman slave to do my housework and mow my lawn.

David, unmatched chromosome numbers can be surprisingly unproblematic, as long as the chromosomes line up well. There are two short chimp chromosomes which line up very well against human chromosome 2 (which was formed by the fusion of those two chromosomes), except for one large section which was apparently "flipped". That section would interfere with alignment far more than mere chromosome number.

What you are thinking of is the problem where one chromosome has nothing at all to line up against. This isn't the case here. In general, where the fusion of two smaller chromosomes or the split of one larger one changes chromosome number, but the DNA sequences involved still have another matching stretch of DNA to pair up with (packaged in the original chromosome(s)), mitosis and meiosis still work just fine. That's how changes in chromosome number in mammals can originate in a single individual, but spread through the population.

It's as possible as creating a Liger.Problem is,who would have the guts to create such a being? How could it live? I could only imagine it living with the scientist who created it.A Humanzee would be shunned by both chimps and human beings.It's ability to speak would be a major factor.If it just ran around grunting,I would consider it an animal.THen it would be a major attraction, appearing on Oprah and other shows.

Differing numbers of chromosomes is hardly enough to stop a human/chimp or human/orangutan hybrid.

In this article, a gibbon (44 chromosomes) mated unaided and successfully with a siamang (another monkey, 50 chromosomes). It is not known whether the hybrid itself could produce offspring, but that wouldn't really matter in this discussion. It is theoretically possible to create a humanzee and we should support this. Imagine bringing a humanzee to your local church. That would be a priceless experience.

Consortium TCSaA: Initial sequence of the chimpanzee
genome and comparison with the human genome. Nature
2005, 437(7055):69-87

Wetterbom A, Sevov M, Cavelier L, Bergstrom TF: Comparative
genomic analysis of human and chimpanzee indicates a key
role for indels in primate evolution. J Mol Evol 2006, 63(5):682-690.

it occcurs to me that both are indeed "something close to 99%".

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Babysitting by males

At one point in the movie, Caesar does some babysitting, which would be very unlikely to happen in nature. “Fatherhood is not a chimp or bonobo thing. The males are at best protective, at worst [in the case of chimps] infanticidal. The carrying and care is for mothers."

Males are not completely indifferent to youngsters, however. "Exceptional males adopt orphans. If the mother is out of the picture, males may carry juveniles … and sometimes are caring for several years,” says de Waal.


18 Answers 18

This speciation will never occur.

Why? A condition Robert A. Heinlein once described as "common bastardy."

People don't always keep their genes to themselves. Humans are well known as what I think of as "false monogamists" even in what are considered monogamous societies. There has never been a noble class in human history that didn't "indulge itself" with the lower classes -- and indulgence of the nature I'm talking about leads to the occasional accidental pregnancy.

This isn't always the duke or king producing offspring on the wrong side of the blanket, as it were, either. There are a number of well documented historical cases of noblewomen producing children that, for one reason or another, could not have been "legitimate."

It only takes a tiny number in each generation resulting from such interbreeding to keep two otherwise separate populations within the same species. This is why humans aren't multiple species today: even those who (like Australian natives) were isolated from other humans for thousands of years (because they weren't there was surely some interbreeding with people from what became Malaysia and Melanesia).


Human and Chimp Ancestors Might Have Interbred

The earliest known ancestors of modern humans might have reproduced with early chimpanzees to create a hybrid species, a new genetic analysis suggests.

Based on the study of human and chimp genomes, the scientists believe the split between the human and chimpanzee lines occurred much more recently than previously thought—no more than 6.3 million years ago and perhaps as recently as 5.4 million years ago.

Human and chimpanzee ancestors began branching apart on the primate evolutionary tree some 9 million years ago, but there are significant gaps in the fossil record. The new analysis suggests that a full split, which scientists call speciation, wasn't achieved for nearly 4 million years and might have occurred twice.

The study was published online today by the journal Nature.

Going back in time

Researchers from Harvard Medical School and the Broad Institute of MIT and Harvard matched sequences of the human genome to the same regions of the genetic code of chimpanzees and several other primate species. DNA is made up of sequences of chemical bases, labeled A, T, G, and C. They compared the codes, letter by letter, and noted where there was a divergence.

Based on an estimated relative mutation rate, they calculated how long it would take to accrue the mutations and determined that millions of years of genetic divergence led to an initial speciation around 6.3 million years ago. From start to finish, complete speciation spanned a much longer time range than in any other modern apes. From start to finish, complete speciation spanned a much longer time range than in any other modern apes.

"The variation is huge," said study lead author Nick Patterson of the Broad Institute. "There are regions of the genome that don't appear to be much more than 5 million years old and there are regions that appear to be 4 million years older than that. The ancestral time over which humans and chimpanzees speciated, where there's no more gene flow, covers 4 million years."

X marks the spot

The team also observed that humans and chimps are very similar on the X chromosome, sometimes referred to as the female sex chromosome. The average age of the X chromosome in humans is about 1.2 million years "younger" than the rest of the chromosomes, and the final change occurred around 5.4 million years ago.

This suggests that after the first speciation at 6.3 million years in the past, early human ancestors may have lived and reproduced with ancestral chimps to produce hybrid primates.

"This would help explain why divergence on X between humans and chimps is so low," Patterson told LiveScience.

Mixing and matching genetic information from two species doesn't always work out well, and hybrid species often have trouble reproducing. The problem generally arises from differences on the X chromosomes.

"In a situation where it's unfavorable to have one X from one species and one from the other, which happens as hybrids reproduce among themselves, you get powerful selection for the good combination," Patterson said. "The X chromosome will fix out and everyone will have the same X."

Patterson explains one possibility for how this could have happened: The initial split occurred around 6.3 million years ago. Sometime after, the descendents of the earliest known human ancestor—the 6.5 to 7.5-million-year-old "Toumai," a biped that probably didn't look much different than chimpanzee ancestors—mated with ancestral chimps and created a hybrid species.

"If that occurred, they might have been compatible enough on X that it would fix out to one species or another," Patterson said. "As it happened, it fixed to chimps, but it could have gone the other way."

This is just one possible explanation for the gap in speciation time, Patterson said, and is not meant to be interpreted as the full answer. Researchers at the Broad Institute are currently working on sequencing gorilla and other primate genomes and searching for similar patterns of evolution to help better tell the whole story.