A synthesis of the theories and concepts of early human evolution
A synthesis of the theories and concepts of early human evolution
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DOI：
10.1098/rstb.2014.0064
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发表时间：
2015-03-05
影响因子：
6.3
通讯作者：
Trauth, Martin H.
中科院分区：
文献类型：
--
作者：
Maslin, Mark A.;Shultz, Susanne;Trauth, Martin H.
目前的证据表明，人类进化的许多重大事件都发生在东非。因此，在过去的二十年里，人们进行了大量的工作来了解非洲的古气候和构造，以便将非洲环境在过去10万年中如何变化的连贯画面放在一起。一种新的共识正在形成，即东非不同寻常的地质和气候创造了一个复杂的、环境非常多变的环境。这种对东非气候的新认识导致了脉冲气候变率假说，该假说认为东非的长期干燥趋势被极端潮湿和干旱的短暂交替时期所打断，这可能推动了人类物种形成、脑化和向非洲的扩散。这个假说是独特的，因为它提供了一个概念框架，在这个框架内，其他的进化理论可以被检验：首先，在宏观尺度上比较系统发育渐进主义和间断平衡；第二，在更集中的人类进化水平上，比较异域物种形成、干旱假说、周转脉冲假说、变异性选择假说、红皇后假说和基于性选择的同域物种形成。有人提出，这些机制中的每一种都可能在这些短暂的气候变化期间作用于古人类，然后产生一系列不同的特征，导致新物种的出现。在直立人的例子中，改变的不仅仅是大脑大小，还有生活史（缩短的生育间隔，延迟的发育）、体型和二态性、允许投掷的肩膀形态、对长跑的适应、生态灵活性和社会行为。进化研究的未来应该是创造基于证据的元叙事，它包含了多种机制，选择最终导致物种形成的不同特征。
Current evidence suggests that many of the major events in hominin evolution occurred in East Africa. Hence, over the past two decades, there has been intensive work undertaken to understand African palaeoclimate and tectonics in order to put together a coherent picture of how the environment of Africa has varied over the past 10 Myr. A new consensus is emerging that suggests the unusual geology and climate of East Africa created a complex, environmentally very variable setting. This new understanding of East African climate has led to the pulsed climate variability hypothesis that suggests the long-term drying trend in East Africa was punctuated by episodes of short alternating periods of extreme humidity and aridity which may have driven hominin speciation, encephalization and dispersals out of Africa. This hypothesis is unique as it provides a conceptual framework within which other evolutionary theories can be examined: first, at macro-scale comparing phylogenetic gradualism and punctuated equilibrium; second, at a more focused level of human evolution comparing allopatric speciation, aridity hypothesis, turnover pulse hypothesis, variability selection hypothesis, Red Queen hypothesis and sympatric speciation based on sexual selection. It is proposed that each one of these mechanisms may have been acting on hominins during these short periods of climate variability, which then produce a range of different traits that led to the emergence of new species. In the case of Homo erectus (sensu lato), it is not just brain size that changes but life history (shortened inter-birth intervals, delayed development), body size and dimorphism, shoulder morphology to allow thrown projectiles, adaptation to long-distance running, ecological flexibility and social behaviour. The future of evolutionary research should be to create evidence-based meta-narratives, which encompass multiple mechanisms that select for different traits leading ultimately to speciation.