Why are women more fertile than men?
We’re all familiar with the stories of the world’s most famous woman-hating scientists: Evelyn Waugh and Anne-Marie Slaughter, Margaret Mead and Ann Druyan.
But what about the world of humans?
What is it about human beings that makes us more fertile?
A new study from the University of Oxford and the University College London (UCL) has found that the female reproductive system is remarkably similar to that of our closest relatives, chimpanzees.
In fact, our own reproductive systems are roughly three to four times more similar to those of other primate species than we are to ours, researchers have found.
The study, published in the journal Evolutionary Biology, used three different methods to study the evolution of human and non-human species.
These included comparing the genomes of three groups of hominid species (Homo sapiens, Homo naledi and Homo erectus) to the genomes from other species, including chimps.
All three groups share similar genetic material, but some differences are significant.
Humans have more genes that code for proteins, for example.
And these differences have been found in many different areas of the genome, from the development of muscles and the formation of blood vessels to the regulation of the immune system.
For example, there are genes for proteins that regulate the production of hormones, like testosterone and cortisol.
But human and chimps have also had different genes for the same gene involved in making the protein, a gene called HLA-DR3, which helps regulate the immune response in humans.
In both humans and chimp genomes, there’s evidence of homoplasy, a feature where two genes have a very similar sequence.
This suggests that the HLA system is very similar between humans and nonhuman species, and may be what explains why the sexes of chimps and humans are so similar.
The results show that human females are very similar to chimps in many ways.
Humans and chimpatans share a relatively simple reproductive system, where each male lays eggs and the female takes them.
The eggs hatch and fertilise the next generation.
In humans, the first generation is usually a male, while in chimps, the next male has the same chances of getting pregnant as the previous male.
However, chimps do not have the reproductive tract of humans, so a female may be able to carry more eggs than a male.
This means that female chimps may be more fertile and may have more children.
The difference between humans, chimpatan and chimpanzee is that both species have a male sex drive.
The males of the two species have evolved a female sex drive, and their sperm are capable of creating more eggs in a female’s body than their own.
When a male wants to fertilise a female, he inserts a special part of his penis into her vagina and inserts his own sperm into her eggshell.
This is called fertilisation.
The fertilised egg then develops inside the female.
The male can control the direction of this development by making her move her body in certain ways, for instance, by moving her head.
This makes the female fertile and allows her to have more offspring.
But the male can also use other sexual behaviours, for which he may ejaculate in her vagina.
This helps him to attract a mate.
When the male wants more offspring, he will also use these other sexual behaviour to attract more females, and this may lead to more sperm being produced in the female’s eggs.
This allows the female to produce more offspring than the male.
But, crucially, both sexes have the same sex drive and, therefore, the same genes for their sex hormones.
The researchers found that in humans, they are also similar in terms of the amount of genetic material that codes for the protein HLA.
The gene responsible for the hormone, HLA DQB1, was not found in either the chimps or humans.
The scientists believe this is because the genes involved in this hormone have similar patterns in humans and the chimp genome, which makes it more likely that it has been transferred to humans from chimps through natural selection.
Humans also have more HLA proteins, which are found in the lining of the reproductive tracts of most other species.
Chimpanzees and humans have many of the same HLA genes.
The team then compared the DNA from these genes in humans with the DNA of the human gene HLA DR1, which is also involved in the control of the female sex hormone, estrogen.
The two genes are highly similar in the human genome, but the human version is much smaller.
So the team compared the size of the HBL1 gene, which codes for estrogen, in the humans with that in the chimpanzees.
The human version of HBL5 gene, for both estrogen and progesterone, was about 1.8 times smaller than the human HBL2 gene, a protein that controls estrogen production.
This indicates that the genes that regulate this hormone in humans have been transferred from chimpan