Descent of Man
In this lecture, beginners can familiarize themselves with basic information and terms used to describe the evolution of humanity beginning with the origin of primates through the comings and goings of Genus Homo.
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Is Crawling babies Overrated?
Posted: Tuesday, July 30, 2002
The number of babies who never crawl is growing - and some researchers say thatís fine
July 30, 2002, Newsday, By Jack Lucentini

Among the Au people of Papua, New Guinea, babies don't crawl. They scoot around on their bottoms, propelling themselves with their hands. The adults call it - but this is a polite translation - "rear-end walking."

David P. Tracer, an anthropologist working among them, decided to do some research into who crawls and why.

His conclusion: For most of human history, babies probably haven't crawled. He presented his findings this spring at the annual meeting of the American Association of Physical Anthropologists in Buffalo.

"Crawling is a relatively recent phenomenon," said Tracer, associate professor of anthropology and director of the Program in Health and Behavioral Sciences at the University of Colorado at Denver.

Among most traditional or tribal cultures, and our ape cousins, infant crawling is virtually absent, Tracer contends. Instead, relatives usually carry the infants, he said, probably an adaptation to keep away germs.

Au children learn to walk perfectly well, he added; they simply take about two to four months longer to do it.

Child development experts, too, say it has become increasingly clear that babies don't have to crawl. The adage that you have to learn to crawl before you can learn to walk simply isn't true, they say, though many medical books imply it is.

Some experts say crawling may even be on the wane among babies today.

Tracer said baby crawling likely arose a few centuries ago in the West, as homes with built-in floors, rather than dirt floors, became common. Without that, parents instinctively don't let their babies have such intimate contact with the ground, he said.

"They'd be basically eating dirt," he said.

Among the Au people, Tracer found babies in their first year of life were carried during 90 percent of their waking hours, usually by a mother, father or sibling.

Similarly, primates - the order of animals to which humans belong - are unusual among mammals in that adults usually carry the young, Tracer said. Among most others, adults drop off the young on or in the ground while they get food, a practice called caching.

Primates' infant carrying is "adaptive," writes Tracer in his paper, "decreasing oral-to-ground contact, parasite transmission, and diarrheal disease risk."

A 1995 Tufts University School of Nutrition study found crawling was the biggest risk factor for diarrheal disease among Bangladeshi children. The second biggest: touching garbage.

Tracer said he has presented his findings on primates and traditional cultures at several professional meetings in the past year. Audience members often pointed out they had seen similar patterns in developing countries, Tracer remarked. "They all said: 'It also occurs to me I haven't seen kids crawl.'"

Many child development experts also now believe crawling is unnecessary, said Karen E. Adolph, associate professor of psychology at New York University and an expert in infant motor development. "In the last 15 years or so, people have talked about crawling as not an obligatory stage," she said.

Indeed, it seems kids are crawling less these days, she added. This may be because in the past decade or more, doctors have been advising parents to not put babies on their tummies to sleep. Doing so may increase the risk of sudden infant death syndrome, in which children stop breathing.

Though there are no good statistics, Adolph said in her laboratory the fraction of babies who don't crawl has grown in the past 15 years, "and those infants who do crawl may begin at later ages". These non-crawling babies usually get around in other ways, such as rolling or pulling on furniture, she said.

Published studies on the value of crawling have given mixed results. A 1991 study by Temple University researchers found that children who didn't crawl were later deficient on specific tests of motor development. But a 1989 study at the University of Padua, Italy, found crawlers were actually more likely to have delayed motor development.

"It's certainly worth rethinking the idea that infants go through a universal developmental program that includes crawling," said Andrea Wiley, an associate professor of anthropology at James Madison University, Harrisonburg, Va.

That may ease many parents' worries, she added. "It's amazing the number of people who say, 'My child has never crawled,' Wiley said. "They're wondering, 'What's wrong with my kid?'"

Books foster this anxiety, she said. "If you read any sort of infant development book on what you should expect your infant to be doing at certain stages, crawling is definitely among them."

A 2000 printing of the Merck Manual of Medical Information Home Edition, a widely used reference, states: "By nine months, the infant sits well and crawls, pulls himself up into a standing position, and says 'mama' and 'dada' indiscriminately." The book also says different children experience such milestones at considerably different ages.

The idea that crawling is a necessary step in development "comes, really, from 'urban myth,'" said Robert W. Steele, a pediatrician at St. John's Children's Hospital in Springfield, Mo. Yet it's a myth compelling enough, incredibly, to have found its way into medical books without serious discussion or questioning, he added.

Adolph said the best medical texts say babies don't have to crawl, but that most books haven't caught up.

"If they don't walk, worry," she said. "But if they don't crawl, don't."

Copyright © 2002, Newsday, Inc.

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