Cranial Blood Flow in Early Hominids

人类大脑形成其巨大的相对大小和复杂的模式的方式和机制是体质人类学中最基本的问题之一。传统上，大脑首先被认为是对最早的人类工具制造的反应，并伴随而来。然而，现在人们知道，早在大脑扩大之前，人类的工具就已经出现在化石记录中了，随后又提出了其他理论来解释这一独特的人类特征。这位研究人员将脑增大解释为脑血流变化的间接结果，并试图检验关于类人猿血液流动模式的两个相关假说。这些假说可以通过检查头骨内部来检验，因为脑膜血管的图案在头骨内部留下了不可磨灭的印记。第一种假设是，脑膜中血管的分支模式区别于两种类型的南方古猿化石。第二，“强有力的”分支模式与较大的颅骨容量相关。后一种假设将在大量的人类和猿类头骨上进行测试，以确定包括人类在内的高等灵长类动物的颅骨容量和血管分支模式之间的相关性的性质。这项研究将提供关于大脑扩大的“辐射体”理论的进一步证据，根据该理论，较大的大脑被认为具有比较小的大脑更复杂的血管网络的特征。

The manner and mechanisms by which the human brain has developed its enormous relative size and intricate mode of patterning is one of the most fundamental questions in physical anthropology. Traditionally, the brain was thought to have first enlarged in response to, and concomitantly with, earliest human tool fabrication. It is now known, however, that human tools show up in the fossil record long before brain enlargement, and other theories have subsequently been offered to explain this uniquely human characteristic. This investigator explains brain enlargement as an indirect result of changes in cerebral blood flow and seeks to test two related hypotheses about the pattern of blood flow in hominoids. These hypotheses can be tested by examination of the interior of skulls, because the pattern of meningeal blood vessels provides an indelible imprint on the interior of the skull. The first hypothesis is that the branching pattern of middle meningeal blood vessels distinguishes between the two types of australopithecine fossil. The second is that a "strong" branching pattern correlates with larger cranial capacity. The latter hypothesis will be tested on a large number of human and ape skulls to determine the nature of the correlation between cranial capacity and blood vessel branching pattern in higher primates including humans. The research will provide further evidence regarding the "radiator" theory of brain enlargement, whereby bigger brains are claimed to be characterized by a more complicated network of vessels than smaller brains.