November 30, 2012
Paternal Voice Recognition Study Provides Hints Of Social Evolution
Lawrence LeBlond for redOrbit.com - Your Universe Online
New research from Arizona State University (ASU) and the University of Veterinary Medicine Hannover in Germany, for the first time, show paternal voice recognition in a not-so-social animal that may provide insight into early primates from which humans evolved.
Studying the grey-mouse lemur, researchers discovered these small primates pay close attention to alarm regardless of where it is coming from, but they are selective when it comes to mating calls from their fathers, paying closer attention to calls from unrelated males than their own kin.
The study´s findings provide the first evidence of paternal kin recognition through vocalizations in a small-brained, solitary species, said lead investigator Sharon Kessler, an ASU School of Human Evolution and Social Change graduate student.
She said that these small lemurs serve as a model for the early primates from which humans evolved. She noted that early primates likely shared similar traits with lemurs such as foraging in dense forests and hunting for food at night in solitude, but also forming and engaging in social groups.
"Species with less complex social systems can be models for early primates, so we can learn about our own evolution. We think that the earliest primates were very much like mouse lemurs," Kessler said. "The study allowed us to go back further in time and to take a deeper approach into time. It suggests that kin recognition through vocalizations was important for primate evolution."
She said the research indicates that sounds made by animals have been a vital tool to recognize kin since before social systems evolved in early primates. By studying animals that forage in solitude rather than in large groups such as monkeys and apes, Kessler said it has allowed them to model how important kin recognition through voice would have been in similar species as far back as 90 million years ago.
The results of the study suggest that “paternal kin recognition can evolve without having a complex social system,” Kessler said in a statement.
Kessler and colleagues began their work in 2008 and set out to examine whether or not animals with smaller brains relative to their body size could recognize kin through vocalizations as they forage alone at night. The team measured calls using various frequencies within the call, duration and intersyllable interval.
While communicating over a distance can be dangerous to some species of animals, due to danger from vocalizations falling upon predatory ears, Kessler explained that lemurs can communicate in a higher frequency that is unable to be picked up by humans and most predators that threaten the lemur. Because the frequency is out of range of predators, the lemurs can communicate without fear.
The study, published today in BMC Ecology, found that females can distinguish their fathers´ vocalizations from unrelated males using mating calls. One explanation of this is that recognition of paternal calls helps the female avoid mating with male relatives, noted Kessler.
Kessler said it is compelling to consider how mouse lemurs can distinguish calls between their fathers and unrelated males since mothers, aunts and grandmothers are the sole creatures raising the young. Fathers do not help with care nor do they share the nest with the mother and babies, so learning a father´s voice while growing up doesn´t seem possible, she added.
The best theory the team can come up with is phenotype matching. Under this hypothesis, if family members sound similar, the females may compare calls of potential mates to their own calls and the calls of their littermates in the nest. Then if they choose mates with dissimilar calls from themselves and their brothers, they know they are choosing unrelated males.