Crawford, author of "The Origins of Native Americans, Evidence from Anthropological Genetics," published this spring by Cambridge University Press, has spent more than 20 years researching questions about the links among indigenous peoples of Asia and America.
As director of KU's Laboratory of Biological Anthropology, Crawford is among a group of scientists using technology to understand time beyond the Ice Age, when early humans began to migrate from Asia into the Americas. In 1989, he became the first U.S. anthropologist to conduct genetic studies in Siberia.
"DNA evidence clearly links today's Asians and American Indians. The debate is about where in Asia the first groups were from and how many groups migrated," says Crawford, who was born in Shanghai and whose paternal grandmother was a Siberian native.
DNA, the molecular stuff crammed with genetic code that transmits hereditary patterns, also offers clues about evolution. Given enough DNA samples from living and ancient populations, scientists can plot expansions and contractions of genetic groups, Crawford notes.
Crawford's research indicates that at least four groups migrated into North America from Siberia at least as early as 30,000 years ago and as recently as 9,000 years ago.
The Eskimo-Aleuts are descendants of the most recent migration, Crawford says. "Eskimo-Aleuts resemble Siberians more closely genetically and physically than any American Indians," Crawford says.
Linguistic differences among American Indian groups and archeological evidence in South America supplement the DNA evidence from Asia and America that supports the four-migration theory, Crawford notes.
His new book evolved, in part, from a course Crawford teaches on the physical anthropology of American Indians. One reviewer described the book as "a comprehensive review of the human biology of American Indians ... that is destined to be a classic."
Crawford uses his field studies with the Eskimos of St. Lawrence Island, the Tlaxcaltecans of Mexico, the Black Caribs of the Caribbean and indigenous Siberians to discuss theories on the peopling of the New World, on the depopulation resulting from Old World contact and on the effects of mixing populations.
"Today's American Indians are survivors of a violent collision of the Old and New Worlds that occurred 500 years ago," Crawford writes. "The total Indian population dropped from about 44 million people to fewer than 10 million" in the first 200 years of contact in North and Central America.
The tragic medical and evolutionary costs of contact continue, but in North and Central America, the Indian population is rebounding due to many factors, including better medical care, Crawford notes.
The New World syndrome prevalent among today's North American Indians is an example of continuing medical costs of the collision, Crawford writes. The syndrome is a trilogy of diseases -- late on-set diabetes, gallstones and gallbladder cancer.
The syndrome doesn't seem to exist among indigenous Siberian peoples despite their genetic similarities with American Indians. Siberians depend on hunting and gathering and comparatively low-fat diets that may protect them, Crawford says.
In North America, confinement to reservations not only helped spread Old World diseases such as smallpox and measles, but compelled lifestyle and consequent dietary changes that contribute to the New World syndrome, Crawford writes. "In South America, Indians were not confined to reservations and do not suffer as high a rate of incidence of New World syndrome."
Black Caribs, descendants of Indian peoples mixed with escaped African slaves, represent the genetic good news evolving from the collision. "They have expanded from fewer than 2,000 people in 1800 to more than 200,000 today," Crawford says. Black Caribs were deported by British colonialists from St. Vincent Island to what is now Honduras. They flourished, in part, because the genetic mix from Africa enabled them to resist malaria.
Story by Mary Jane Dunlap (785) 864-8853