Thursday, March 8, 2012

Your inner fish

Paleontology hit the headlines a few years ago when paleontologists discovered a fossil fish, Tiktaalik roseae, that showed the beginnings of digits, wrists, elbows and shoulders, as well as a skull, neck and ribs that resemble those of tetrapods like today's familiar four-legged land animals. Paleontologists suggest that it was an intermediate form between fish which lived about 385 million years ago, and early tetrapods which lived about 365 million years ago. Its mixture of fish and tetrapod characteristics led one of its discoverers, Neil Shubin, to characterize Tiktaalik as a "fishapod". Like any self-respecting fossil Tiktaalik has its own homepage.

Neil Shubin wrote a popular science book  'Your Inner Fish' which is a very easy and highly recommended. We tend to focus on those areas where we have 'improved' on our fish-like ancestors (walking upright, doing pushups, inventing calculus etc) but what I found fascinating, was a discussion of olfaction (smelling) and how it's all been downhill since our aquatic past.

The human genome only contains about 23,000 protein-coding genes - which itself is an amazing fact. The other 98.5% of our genome consists of non-coding genes, regulatory sequences, introns and endogenous retrovirus sequences.

About 1,000 of those 23,000 protein-coding genes code for different odor receptors but less than half of them are functional in modern humans. Which says a lot about the importance of different senses in the evolution of humans from an aquatic ancestor (smell) to a terrestrial life (vision). Our evolutionary history is revealed in our genes.

Finally, Neil Shubin, appeared on the Colbert Report in 2008 and did a pretty good job.


(Parts of this post were recycled from previous blog postings).

1 comment:

Anonymous said...

nice idea.. thanks for posting.