How Science Is Done (cont'd)


June 09, 2013

Two papers published in recent weeks demonstrate again the rigor of the scientific method. The first  concerned a 50,000-year-old Neanderthal tooth from Belgium, while the other pertained to the controversial Australopithecus sediba fossils from South Africa.

In a paper published in Nature on May 22, Christine Austin and other researchers wrote that examination of barium levels in a molar from a juvenile male Neanderthal indicated the individual when an infant subsisted on mother’s milk exclusively for the first seven months of his life. He continued to be nursed for another seven months, receiving other food as well. He was no longer breast-fed after 14 months of age. Contemporary human infants are weaned more than two years after birth on average and contemporary chimpanzee infants are nursed for more than five years. Nursing has a contraceptive effect and weaning can be used in planning the spacing of offspring.

The rigor of the scientific method is demonstrated by the reaction of other scientists to this paper. There was widespread comment on the choice of specimen and the methodology. Researchers question the reliance on a single tooth on which to draw conclusions about Neanderthal weaning practices. Other researchers pointed out that  barium in teeth can be deposited from other sources than mother’s milk and reliance on barium is somewhat out of date.

Read the Nature paper and the related article in the New York Times.

More scientific skepticism at work. In the May 30 2013 issue of Nature, William H Kimbel, Director of the Institute of Human Origins at Arizona State University cast considerable doubt on the recent announcement in the journal Science (see the report on this website) concerning fossilized partial skeletons found at Malapa Cave in South Africa and named Australopithecus sediba). Kimbel, a leading paleoanthropologist and specialist in systematics,  in an article entitled alliteratively "Hesitation on Hominin History" briefly but trenchantly analyzes each of the most recent five papers by members of a team led by Lee Berger of the University of the Witwatersrand.

Not all scientific writing need be without humor: Dr. Kimbel pointedly refers to Monty Python and the Ministry of Silly Walks.

Read Kimbel’s comments in Nature.

A related matter is how scientific papers are reviewed for publication.  Papers appearing in journals like Science and Nature are peer reviewed. After a scientist prepares a paper describing his or her findings the paper is submitted to a journal for publication. The editor of the journal sends the paper to other scientists working in the same field, asking for their assessment of the paper's quality, methodology and relevance. This panel of the author’s peers returns its comments and then the  editor decides whether to publish the paper. The members of the peer review panel remain anonymous. In some cases the paper is rejected and in other cases published after changes recommended by the panel are made. Some paleoanthropologists have expressed surprise that both the Austin barium paper and the five papers by the Berger team survived peer review and were published in Nature and Science respectively.