新的研究结果显示，在印度尼西亚发现的近似人类化石，应该就是人类的一支。自从6年前发现了这个以电影《指环王》内容中的小矮人而被昵称为“霍比特人”的化石之后，学界便一直为如何将之分类而争辩不休。
“霍比特人”的身高只有大约4英尺，脑部大小和黑猩猩差不多。据认为，“霍比特人”是从大约一百万年前抵达印尼弗罗里斯岛的人类远祖演化而成的侏儒。
但是不赞同此一理论的人士则说，“霍比特人”的脑部太小，而一个正常大小的人类的脑部不可能会因为演化而缩小到这种地步。
但是在《自然期刊》上发表的研究报告说说，在研究了侏儒河马的头骨之后，证明同类动物的头骨在演化过程当中的确可以缩小很多。
参与研究的英国自然科学博物馆的温登博士说， “霍比特人”一直让科学家们想不透，因为“霍比特人”的脑部只有黑猩猩一样的大小。这是在其他远古人类研究上从来没见到过的现象。
温登博士认为，如果以距离现代人类较近的直立猿人的身子和脑部的比例来计算的话，“霍比特人”脑部比较小，其实也不是不合道理的。
另外一个针对“霍比特人”足部所作的研究，则是把结果发表在《人类进化期刊》上。这个研究认为，“霍比特人”是从东南亚本地的远古人类进化而来的。
这两个研究的结果，虽然不一定证明了“霍比特人”绝对是人类的远祖的一支，但是却证明了人类的进化史要比以前想象的更加复杂。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 459, 85-88 (7 May 2009) | doi:10.1038/nature07922
Insular dwarfism in hippos and a model for brain size reduction in Homo floresiensis
Eleanor M. Weston1 & Adrian M. Lister1
1 Department of Palaeontology, Natural History Museum, London SW7 5BD, UK
Body size reduction in mammals is usually associated with only moderate brain size reduction, because the brain and sensory organs complete their growth before the rest of the body during ontogeny1, 2. On this basis, 'phyletic dwarfs' are predicted to have a greater relative brain size than 'phyletic giants'1, 3. However, this trend has been questioned in the special case of dwarfism of mammals on islands4. Here we show that the endocranial capacities of extinct dwarf species of hippopotamus from Madagascar are up to 30% smaller than those of a mainland African ancestor scaled to equivalent body mass. These results show that brain size reduction is much greater than predicted from an intraspecific 'late ontogenetic' model of dwarfism in which brain size scales to body size with an exponent of 0.35. The nature of the proportional change or grade shift2, 5 observed here indicates that selective pressures on brain size are potentially independent of those on body size. This study demonstrates empirically that it is mechanistically possible for dwarf mammals on islands to evolve significantly smaller brains than would be predicted from a model of dwarfing based on the intraspecific scaling of the mainland ancestor. Our findings challenge current understanding of brain–body allometric relationships in mammals and suggest that the process of dwarfism could in principle explain small brain size, a factor relevant to the interpretation of the small-brained hominin found on the Island of Flores, Indonesia6.
