7. Top-heavy and meat-loving

The first possible cause of extinction I would like to examine is their skull size. Human heads are biologically at its extremity in regards to its size. If our heads were larger than it is now, then it wouldn't be able to pass through the birth canal at birth.

There are crevices called fontanels in the skull of a newborn baby. Among those crevices is the anterior fontanel at the parietal. The anterior fontanel is large enough that the pulsing of the cerebral surface can been seen. Why are babies born with crevices in their skulls when it should be protecting the all critical brain? The reason is that if human head with the current size were covered with hard, untransformable bone, then the head would not be able to pass through the birth canal.

The unconnected skull makes it possible for the head to transform, and accordingly, we can narrowly pass through the birth canal to finally come into being.

Therefore the Neanderthals, whose heads were larger than those of the Cro-Magnons, must have had hard labor. The occurrence of abnormality during labor must have been higher with the Neanderthals. It is highly possible that this small difference in birthrate could have caused the Neanderthals to suffer defeat against the Cro-Magnons in their fight for existence. The swelling of the near-extinct Neanderthals' cranial capacity may also have hastened their extinction.

The next possibility is the difference in eating habits between the Cro-Magnons and Neanderthals. According to research by Paul Pettitt of Oxford University, Fred Smith of Northern Illinois University and Eric Trinkaus of Washington University, 90 percent of the food the Neanderthals had been eating was meat.

Eating habits can be roughly identified by measuring the radioisotopic signatures recorded in the animals' bones according to its diet. This research group measured the radioisotope called nitrogen 15 extracted from the Neanderthal's skeleton of 28,000 years ago unearthed in Croatia. It turned out that the measurements showed an extremely high level. This result indicated that the Neanderthals were as carnivorous as the lions are.

At the same time, research using the same method revealed that the Cro-Magnons were omnivorous, eating much more fish.

The Neanderthals, who were skilled in hunting, may have hunt up every large game animals, leading them to extinction.

On the contrary, the Cro-Magnons, being omnivorous, were highly capable of adapting to the environment, and therefore replaced the Neanderthals and increased its population in Europe after large game such as the mammoths had died out.

Some researchers think that the Cro-Magnons, living much more on fish, had more intake of DHA, a substance in fish contributing to the development of brains, had their brains developed and accordingly forced the Neanderthals to extinction. But if such could be true, the Japanese, with the highest consumption of fish in the world, should have brains that are exceptionally developed. Considering such the situation, I can't but doubt the credibility of this theory.

Translated by Rie Ishida