The Making of the Fittest DVD (HHMI). A trilogy of short films revealing the evolutionary process in action:
Natural Selection and Adaptation:
The rock pocket mouse. A very good example of Darwin’s theory. This video took place in New Mexico. Scientists did a study on these mice that had adapted to life on black lava flows against a bare desert. The lava flow is about 1,000 years old.
Predators of the mice are owls, rattlesnakes, foxes, hawks, jackals and coyotes. Most of these predators rely primarily on sight to catch their prey.
There was a black mutation in the gene and that mutation wasn't weeded out because of the background they were on, so the mutation spread. The mice with the normal (light-coloured) fur gene died out, and the ones with the black fur did not.
It was interesting that the black fur appeared only on the mice backs and heads, not on their bellies. The dark fur was not needed on their bellies, in order for the population to survive.
The scientists explained that, if the mutation gave the mice a 1% advantage of survival on the dark lava flows, it would take 1,000 years for 95% of the population to have dark fur. A 10% advantage would cause an evolutionary change in a population, within 100 years.
The Birth and Death of Genes:
On December 26, 1927, a Norwegian expedition (Norvegia) to Bouvet Island, an island at the edge of Antarctica, discovered a scaleless fish, later named crocodile fish or ice fish.
This was a very intriguing and special genetic discovery. The ice fish almost looks like an albino fish, crocodile-like. This fish has no red blood cells, because of a genetic mutation. The fish looks weird and disgusting. Its skin is translucent and it’s possible to see its brain and heart and optic nerves through its skin. This is primarily because the fish has no scales.
With no red blood cells or hemoglobin (the protein that delivers oxygen to the cells of the body), scientists wondered how blood could flow in the ice fish. The ice fish can survive without hemoglobin because of the high oxygen content in the frigid waters in which it lives.
Art Devries discovered antifreeze proteins in the 1990s, in fish that live in waters with a temperature of -1.8 degrees celsius. These proteins resulted from an accidental mutation of the ancestral genes.
Natural Selection in Humans:
This video highlighted the work of Tony Allison, who studied the connection between sickle cell disease and malaria in Kenya.
Dr. Allison took many blood samples across Kenya and detailed maps showed the correlation between sickle cell disease and malaria, near Lake Victoria and the coast. Sickle cell disease appeared in very low frequencies in the high country of Nairobi, where malaria is not a problem.
We learned the meanings of homozygous and heterozygous. Tony Allison explained that genes are lined up on chromosomes and humans have pairs of them, with the exception of the sex chromosomes. The chromosomes can be the same or different. If they are the same, they are homozygous and if they are different, they are heterozygous.
It was discovered that carriers of the sickle cell gene, were seemingly protected from malaria. The sickle cell mutation compromises the ability of the parasite to reproduce. Protection from malaria comes at the cost of more sickle cell disease in the population.
Tony Allison believes this proves that human evolution is taking place in our living population. And this is evidence that environment is the catalyst, rather than genetics alone.
