Penn state scientist Nina Jablonski has been studying early humans and the evolution of skin, and presented her latest research at the annual meeting of the American Association for the Advancement of Science in Boston, saying that hairless skin first evolved in humans as a way to keep cool.
Over the years, the distinguished professor of Anthropology says that humans then began to decorate skin to increase attractiveness to the opposite sex and to express, among other things, group identity.
"We can make a visual impact and present a completely different impression than we can with regular, undecorated skin," explains Jablonski.
Jablonski says that both males and females use forms of skin decoration to become more attractive to the opposite sex. Whilst she says historically, men would adopt tattoos and body paint, women have turned to make-up.
"We can paint a great design on our bodies and use those designs to send all sorts of messages or express group memberships," said Jablonski.
As such, the cosmetics industry has taken off as people look to preserve their skin, and enhance their appearance.
According to the researcher, studying skin is difficult because it can be preserved only for a few thousand years, unlike bones and fossils, which last millions of years.
In this study, Jablonski and other researchers based their estimate on when humans evolved hairless skin on the study of the fossil record and an examination of the molecular history of genes that code proteins that help produce skin pigmentation.
"We find a lot of evidence of when humans began to lose hair based on molecular genetics," said Jablonski.
Prior to the idea that humans evolved hairlessness as a mechanism to cope with body heat, some researchers believed that hairlessness resulted from evolution from a common aquatic ancestor, Jablonski said.
However, the theory, often referred to as the aquatic ape theory, does not match the genetic, fossil and environmental evidence, she said.
Jablonski adds that prior to the evolution of mostly naked skin; decoration would not be possible as humans were still covered with fur.