by Dan Falk
It was 150 years ago this year that Charles Darwin published his extraordinary treatise on evolution, On the Origin of Species. Despite its length, the famous book contained just one diagram – a simple depiction of the “tree of life,” an array of branching lines that shows how all living things on our planet are ultimately interrelated.
It’s a picture that lies at the very heart of the work of U of T Scarborough anthropologist Michael Schillaci. He studies the evolution of human populations in a diverse array of settings, past and present; and he also works with living monkeys and other primates, both in captivity and in the wild. And in spite of their differences, he sees unmistakable similarities between human beings and our primate cousins.
“For me, when I look into a monkey’s eyes, there’s a lot going on there,” says Schillaci, who teaches in U of T Scarborough’s Department of Social Sciences. From his extensive field work with macaque monkeys in Southeast Asia, he’s seen aspects of monkey behaviour that are strikingly human: They show signs of sophisticated non-verbal communication, a knack for problem-solving, and a vast array of emotions – anger, anxiety, fear, contentment. “I don’t want to make them sound like little humans -- they’re not like that,” Schillaci says. “But they’re intelligent and highly social animals.”
As fascinating as his primate research is, it’s never just about the monkeys; the bigger picture always lurks in the background. “I’m interested in using primates as a model for understanding human evolution,” says Schillaci, who also teaches a graduate anthropology course at the St. George campus.
Consider one of the most hotly-debated questions about recent human evolution – the fate of the Neanderthals, an offshoot of the human family tree that flourished in Europe and western Asia from about 130,000 years ago until about 28,000 years ago. During the final phase of their existence, Neanderthals lived in southwestern Europe alongside modern Homo sapiens. The question is, did they do more than spy on each other from a distance? And if there was interbreeding between the two varieties of humans, could any Neanderthal genes have survived to the present day? The experts have yet to reach a consensus on this question, but Schillaci suspects that there was at least some degree of hybridization – that is, he believes there were at least occasional Neanderthal-human matings. “This is a sexy topic,” Schillaci says, “because people want to know if there are Neanderthal alleles [gene sequences] existing in any modern-day populations” – that is, whether you and I are carrying a little bit of Neanderthal DNA in our bodies.” In spite of the occasional hook-ups between Neanderthals and humans, however, Schillaci believes that Neanderthal alleles have not been passed down. “The hybrids may have been selected against; they may have had a reduced ‘fitness’,” he says – that is, whatever offspring may have resulted from such pairings didn’t fare as well as their competitors in the struggle for survival and reproduction, and in turn left fewer offspring behind. In spite of occasional contact between the two species, the Neanderthals were not likely to have left a genetic legacy, he says.
This is where Schillaci’s research with monkeys comes in. His PhD thesis focused on macaque monkeys living on Sulawesi (formerly Celebes), a large island in Indonesia. The island is shaped somewhat like a starfish, with four peninsulas sticking out in different directions. Each peninsula, it turns out, has its own distinct species of macaques. “But where the four peninsulas meet, in the middle, you have ‘zones of contact’,” Schillaci explains.
These different macaque species, then, are playing out the same scenario that humans and Neanderthals acted out tens of thousands of years ago: Similar but not identical species are sharing the same landscape at the same time. And where the different macaque species meet, near the centre of the island – you guessed it – inter-species monkey-business ensues. Apparently unperturbed by slight anatomical and biological differences, these different macaque species set about making little monkeys. “They hybridize,” Schillaci says.
And once again, the monkeys provide clues about our own evolution, shedding light on physical variation between human sub-groups, growth patterns, and even the transmission of disease. “I use them as a model,” Schillaci says.
Among the pathogens he studies is West Nile Virus. The virus is transmitted by mosquitoes and is capable of infecting humans, birds, and several different species of mammals, including apes and monkeys. Schillaci says the virus has turned up in captive primate populations in Ontario, on occasion in zoo animals and in wildlife sanctuaries. Although infected primates pose no risk to humans, he says that keeping an eye on captive primates could help in monitoring outbreaks – not only of West Nile, but of other insect-borne infections.
Public health, bio-archaeology and human evolution are all aspects of his research, which Schillaci describes as both interdisciplinary and multidisciplinary. “As a field, bio-anthropology focuses directly or indirectly on evolution -- primarily human evolution. Unlike most biologists, biological anthropologists are interested in the social or cultural context of biological variation and evolution. We’re interested in humans and primates as cultural and social animals.” The exciting and developing field of bio-anthropology is said to transcend typical academic categories. According to his colleagues, Michael Schillaci’s research is breaking important ground in a way that straddles the boundaries of traditional disciplines and raises vital questions about the very nature of our evolutionary history.
One of Schillaci’s recent investigations examined an earlier but quite pivotal episode in early human evolution: the initial migration of Homo sapiens out of Africa.
In an article published in the Journal of Human Evolution, Schillaci examined “morphometric” data – measurements of physical characteristics, including precise measurements of the head – from dozens of modern human cultures, comparing the data from each group to that of its neighbours. While there has long been a consensus that modern humans streamed out of Africa and into southern Asia about 50,000 years ago, Schillaci’s research also supports a more controversial idea – that of an earlier expansion, between 100,000 and 75,000 years ago.
Anthropologists suspect that if there was an earlier migration, it followed a coastal route along southern Asia. Because sea levels were lower at that time, the route is likely under water now, Schillaci explains. But he can guess at one thing those early travellers carried with them: viruses. Interestingly, the present-day distribution of some viruses seems to support the story of the two migrations. “The viruses co-evolved with their hosts,” Schillaci says.
The out-of-Africa story also highlights some of the misconceptions about evolution that Schillaci struggles to drive home to his students. Evolution is defined as a change in gene frequency within a population from one generation to another. When most students think of evolution, he says, they tend to think only of natural selection and adaptation to the environment. But, he explains, evolution can occur through other processes such as genetic drift and gene flow, both of which influence genetic variation. In fact, Schillaci says, gene flow and genetic drift have been major processes affecting the global distribution of human genetic variation. “When I’m teaching, I drive home what the definition of evolution is, and I struggle to get that message across,” Schillaci says.
It seems to be working. Professor Ted Relph, chair of the department of social sciences, notes that one of the impressive things about Michael Schillaci is that he has a team of undergraduate and graduate students working with him on campus and often accompanying him into the field. Relph says, "It’s clear that bio-anthropology is an exciting field that attracts some of our best students. Several undergraduates working with him have presented at conferences or been published in peer-reviewed journals – accomplishments that can outweigh GPA when applying for grad school." Schillaci adds that his students’ success can be a model for other departments. “It’s something I’m proud of,” he says.