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The fossilized pelvis of a Homo erectus woman who lived 1.2 million years ago on the banks of an Ethiopian river has been discovered, and while researchers say it casts new light on human evolution, some of their conclusions are challenging previous theories about these early human ancestors. The pelvis reveals a short, squat woman who wasn’t built for long-distance running, but also a woman with a wide birth canal to accommodate big-brained infants.

Study coauthor Scott Simpson says the pelvis’s wide birth canal indicates that hominds’ increasing brain size was a driving factor in human evolution. Getting through the birth canal is “the most gymnastic thing we ever do,” he says. To accommodate big-brained babies, humans must have developed larger and wider birth canals over time, but with few pelvic fossils, researchers had little idea when these changes began. The Busidima pelvis shows that a wide birth canal was already in place 1.2 million years ago [New Scientist].

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A new analysis of the skulls of three Neanderthal babies shows that the cranium of a newborn Neanderthal was about the same size as that of a newborn Homo sapiens, and that the Neanderthal children grew faster than modern humans in the first few years of life. The report on the young skeletons, which date from between 45,000 to 50,000 years ago, adds fuel to the debate over how similar Neanderthal culture was to that of our early Homo sapiens ancestors.

A big-headed infant skeleton found in Russia suggests that childbirth was no easy task for for Neanderthal women. Neanderthal mothers had slightly larger birth canals, but the prominent face of Neanderthal babies made it just as hard to push out as a modern human. This suggests that both groups had the social structures needed to help with childbirth [New Scientist].

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In a controversial new procedure, doctors removed the hearts from three severely brain damaged infants soon after the babies were removed from life support and transplanted the organs to three other infants, where the hearts were restarted. The news is raising complicated questions about when a patient can be declared dead, and whether doctors are pushing an already controversial organ-retrieval strategy beyond acceptable legal, moral and ethical bounds [The Washington Post].

The hearts of the three donor babies stopped beating soon after their ventilators were removed. In the first case, the Denver team waited three minutes after what appeared to be the last heartbeat. But because there has never been a case where the heart restarted itself after 60 seconds, they waited only 75 seconds for their next two cases [Reuters]. All three babies who received new hearts would have died without the transplants; six months after the operations, all three were doing fine. Doctors believe the swift organ removals from the donor babies increased the odds of survival for the recipient babies.

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Researchers have the best evidence yet that the brain chemical serotonin plays a role in sudden infant death sydrome (SIDS).

In a new study, researchers genetically engineered mice to have low levels of serotonin at birth, and found that more than half of the mice abruptly died before they were 3 months old. More intriguing, they had erratic episodes where their heart rate would drop and, five to 10 minutes later, so would their body temperature, [study author Cornelius] Gross reported. Sometimes they died in the midst of what Gross calls those crises, other times afterward [AP].

Serotonin is most commonly known as a mood regulator involved in depression, but it also helps control some of the body’s most basic functions, including breathing, heart rate, and body temperature. The mouse study supports earlier data gathered from the autopsied brain tissue of SIDS babies, which showed alterations in brainstem nerve cells that communicate using serotonin.

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After years of hectoring new parents about the need to keep babies protected from the sun’s fierce ultraviolet rays, doctors may be about to swing back the other way. A new study shows that many infants and toddlers aren’t getting enough Vitamin D, which is produced in human skin during exposure to sunshine.

Vitamin D is essential for bone growth and absorption of calcium in the digestive tract, and also plays a role in regulating the immune system. But doctors disagree on the severity of the problem posed by the low vitamin D levels found in the study, and are also divided on what course of action to recommend.

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