造成我们独特认知能力进化的代谢变化表明,人脑的容量可能已经被推至极限。今天发表在《基因组生物学》(Genome Biology)上的研究为精神分裂症是人脑进化的一个代价昂贵的副产物这一理论增加了份量。
德国马普进化人类学研究所的Philipp Khaitovich和合作者对健康者及精神分裂症病患的人脑进行了研究,并将其与黑猩猩和恒河猴的脑子进行了比较。正如Khaitovich所解释的,这些研究人员寻找基因表达及代谢物浓度方面存在的差异,并“通过结合来自2个研究方向(即进化学和医学)的生物学数据,确认了与人类认知能力的进化有关的分子机制。”
以前曾经有人提出一种观点,即某些神经科疾病是人类在进化时代谢及脑容量增加的副产物。但在这一新的研究工作中,文章的作者应用了新的技术手段真正地测试了这一理论。
他们发现了在人类进化过程中发生的分子变化并对在精神分裂症病患中所观察到的分子变化进行了思索。精神分裂症被认为是一种认知功能(如语言能力和复杂的社会关系)受到影响的精神科疾病。他们发现,精神分裂症患者中的那些与能量代谢特别有关的基因和代谢物表达水平的变化同时也会在进化中快速地改变。据Khaitovich披露:“我们新的研究表明,精神分裂症是人脑进化所招致的代谢需求增加的一种副产物。”
文章的作者得出结论,这项工作为更为细致的研究工作铺平了道路。Khaitovich说:“我们的大脑在所有的物种中是独特的,因为它们有巨大的代谢需求量。如果我们能够解释我们的大脑是如何承受这一巨大的代谢流的话,我们将会有更大的机会来了解脑是如何工作的及为什么它有的时候会崩溃。”(生物谷Bioon.com)
生物谷推荐原始出处:
Genome Biology,doi:10.1186/gb-2008-9-8-r124,Philipp Khaitovich,Sabine Bahn
Metabolic changes in schizophrenia and human brain evolution
Philipp Khaitovich , Helen E Lockstone , Matthew T Wayland , Tsz M Tsang , Samantha D Jayatilaka , Arfu J Guo , Jie Zhou , Mehmet Somel , Laura W Harris , Elaine Holmes , Svante Paabo and Sabine Bahn
Background
Despite decades of research, the molecular changes responsible for the evolution of human cognitive abilities remain unknown. Comparative evolutionary studies provide detailed information about DNA sequence and mRNA expression differences between humans and other primates but, in the absence of other information, it has proved very difficult to identify molecular pathways relevant to human cognition.
Results
Here, we compare changes in gene expression and metabolite concentrations in the human brain and compare them to the changes seen in a disorder known to affect human cognitive abilities, schizophrenia. We find that both genes and metabolites relating to energy metabolism and energy-expensive brain functions are altered in schizophrenia and, at the same time, appear to have changed rapidly during recent human evolution, probably as a result of positive selection.
Conclusions
Our findings, along with several previous studies, suggest that the evolution of human cognitive abilities was accompanied by adaptive changes in brain metabolism, potentially pushing the human brain to the limit of its metabolic capabilities.