Why are humans more diverse as a species than other animals?

Humans are more complex and are more capable of performing physiological and psychological activities compared to animal species. Whether based on science or from some divine perspective, humans have powerful cognitive ability and, therefore, superior over other animal species on the planet. But when we look into its diversity, humans seem more diverse. However, recent studies suggest we are not more varied than other animals.

If we simply look into humans’ skin color, body structure, hair, eye color, and language, we can say that humans are seemingly diverse. Yet how much of this diversity is genetically encoded, and how deep are these differences between human groups?

Humans are genetically far less diverse compared with many other mammalian species – a counterintuitive finding, given our massive population and worldwide distribution.

For example, Pan troglodytestroglodytes, the chimpanzee subspecies that live just in central Africa, have higher levels of diversity than the entire humans. Moreover, there are higher genetic differentiation between the western (P. t. verus) and central (P. t. troglodytes) subspecies of chimpanzees than that between human populations.

What new researches say?

Some researchers reported important new insights into evolution. Following a study of mitochondrial DNA from about 5 million specimens, the research encompasses 100,000 animal species.

Researchers from The Rockefeller University in New York City and the Biozentrum at the University of Basel in Switzerland, extracted “big data” insights from the world’s fast-growing genetic databases and reviewed extensive literature in evolutionary theory, and published several conclusions in the Human Evolution journal.

Some conclusions included are the following:

  • In terms of genetic diversity, the 7.6 billion humans on Earth are exceptional in the animal kingdom. However, there is only a tiny average genetic difference in mitochondrial sequences between any two individual people on the planet, which is nearly the same as the average genetic difference between other animals like a pair of house sparrows and pigeons, or robins. Only a 0.1% or 1 in 1,000 typical difference makes up a DNA sequence within a species, including humans.
  • As proposed by some researches, population size is a factor of human diversity, suggesting that more extended isolation of a population results in reproduction. Also, the isolated communities’ members will only reproduce with each other, and they will start to diverge from other communities’ members. Over time, these divergences will become so great that members from different isolated communities will no longer produce healthy offspring.

Meanwhile, the genetic variation or the average difference in mitochondria DNA between two individuals of the same species does not increase with population size. The evolution is continuous, and the lack of genetic variation offers insights into the timing of the species’ emergence and its conservation.

The hypothesis is supported by a mass of evidence that most species, be it a bird, a fish, or a moth, like modern humans, arose recently and have not had time to develop a lot of genetic diversity. The 0.1% average genetic diversity within humanity today has no significant difference between the distinct species about 100,000—200,000 years ago. The same applies to over 90% of species on Earth today.

  • There is a specific mitochondrial sequence on each species, and members of the same species have a tightly similar or identical mitochondrial sequence.The research suggests that species are “islands in sequence space” with few intermediate “stepping stones” surviving the evolutionary process.

There is a novel use of the collection to examine the range of genetic differences within animal species ranging from bumblebees to birds. The researchers have found out that there is only a minute genetic variation within most animal species and an apparent genetic distinction between a given species and others.

According to Jesse Ausubel, Director of the Program for the Human Environment at The Rockefeller University, if a Martian landed on Earth and met a flock of pigeons and a crowd of humans, one would not seem more diverse than the other according to the basic measure of mitochondrial DNA. Mark Stoeckle, Senior Research Associate and Research Associate David Thaler of the University of Basel, Switzerland, led the research.

Dr. Stoeckle said that at a time when humans place so much emphasis on individual and group differences, maybe we should spend more time on the ways in which we resemble one another and the rest of the animal kingdom. He also stated that culture, life experience, and other things could make people very different, but we’re like the birds in terms of basic biology.