Humans and Hobbits

A recent publication¹ concerning the discovery of what was apparently a population of 1 meter tall humans has, not surprisingly, generated quite a bit of news over the past several days. Skeletal material from at least eight individuals has been excavated from a limestone cave on Flores Island. In addition to their short stature, other skeletal changes have prompted scientists to establish a new species Homo floresiensis. The journal Nature has developed a special site on Flores man, affectionately referred to as 'hobbits' by some reseachers.

When I first heard this news, it immediately brought to mind a paper I had read several years ago on the broader phenomenon of evolutionary miniaturization.² I went back to my files and dug this one out and in my margin notes found "why not humans?" The phenomenom of miniaturization is very widespread in nature and occurs in all metazoan taxa. It is also especially common on islands. One possible mechanism for reduction in body size involves a reduction in genome size coupled with a concommitant reduction in cell size. The fact that much of our genome appears to be "junk DNA" makes this an especially intriguing notion. Furthermore, another Nature article last week³ reported that mice with 3% of their genome deleted can develop normally (howevery they did not note any significant reduction in cell or body size). Interesting stuff in any case...stay tuned for future developments. /dps

¹Morwood MJ. et al. 2004. Archaeology and age of a new hominin from Flores in eastern Indonesia. Nature 431: 1087-1091.

²Hanken, J. & Wake, D.B. 1993. Miniaturization of body size: organismal consequences and evolutionary significance. Ann. Rev. Ecol. Syst. 24: 501-519.

³Nobrega, M.A. et al. 2004. Megabase deletions of gene deserts result in viable mice. Nature 431: 988-993.