The first scientific study of how human groups change over time has found the most recent evolution of human social norms is consistent with the first evolution of humans.
The study, published in Science, looked at the genomes of two groups of chimpanzees and found that the groups evolved together, in the same way that modern humans have, and that there was a “shared common ancestor” in both groups.
“These findings are consistent with previous findings that chimpanzees and humans evolved from a common ancestor, which was either chimpanzees or modern humans,” says Danielle McLean, who led the study.
“We see this as the most consistent evolutionary scenario for humans and chimpanzees.”
The finding that the evolution that resulted in human social behaviour is consistent was not immediately evident.
“This is one of the first studies to show that the social behaviour in chimpanzees and other primate species is more closely related to human evolution than to the evolutionary history of other animals,” McLean told BBC News.
“The idea that the chimpanzees and our own evolutionary history could be linked is intriguing.
It shows that it is possible to look at the same animals and see patterns.”
Social norms have been studied in the past, but this is the first study to use whole genomes.
The study is the latest in a series of studies using whole genome sequencing to analyse how social behaviour evolves in animals, such as the chimpanzee.
“Our study has shown for the first time that the shared ancestor is a common chimpanzee ancestor, but we need to get much further before we can say how this happened,” Mclean said.
The new findings provide a new insight into how human group behaviour evolves, and provide important insights into how the evolution and spread of social behaviours in the natural world has evolved over the last several million years.
McLean and her colleagues studied the genomes from a group of two chimpanzees living in the wild in the Brazilian Amazon in 1998.
The two chimps, known as Drosophila, are the smallest members of the group, with just a few hundred individuals.
McLean’s team sequenced the genomes for the three individuals in question, and found there was “an unusually high frequency of close kin, a strong genetic association, and a high frequency for common genes”.
In humans, “we know that the same genes have been passed down to all of our species for millions of years,” McLeod said.
“But it is really hard to get the same DNA sequence from an animal and to see if it is shared with another species.
It is very rare for the same gene to be shared between humans and another species.”
McLean’s findings also found that these same genes were also present in the genomes and DNA of the two chimpanzees in the current study.
“We can see that this is an evolutionary relationship,” she said.
“This is a relationship that has been shown to be important for the socialisation of animals and for the evolution in humans, as well as the spread of human societies across the planet.”
McLeod believes that the evolutionary implications of this discovery are potentially profound.
“It is not surprising that we see shared ancestry between chimpanzees and modern humans, because there are shared evolutionary pathways for these two groups to have evolved,” she added.
“They also share the same genetic structure in their genomes, so it is likely that this shared ancestry was also shared between modern humans and chimps in this particular study.”
McKenzie’s work was supported by the Natural Sciences and Engineering Research Council of Australia (NSERC), the Australian Research Council, and the University of Melbourne.