Birthplace of Charles Darwin

Charles Darwin’s birthday is today – his evolutionary theory is one of the cornerstones of anthropology: the study of humankind. It was in the Galapagos Islands, with their myriad natural anomalies, that Darwin developed what he called the theory of “natural selection, ” which forms the basis of evolutionary theory, in all the sciences.

Darwin and Natural Selection

Darwin’s theory of natural selection rests on phenomena that are subject to direct observation and experimentation: In every species, there is a range of variation of specific traits (hair and skin color, for example.)

Not every individual in any given species reproduces. In a nutshell, Darwin’s theory states that those who do reproduce pass down their specific traits to their offspring. If a certain trait is more advantageous in a specific environment, then the carriers of that trait are more likely to survive into adulthood and to generate offspring than those who do not have that trait.

Cumulatively, over generations, the traits that are advantageous for a species will proliferate. Darwin originally termed this process “descent with modification.” By the late 1860s, he started to call it “survival of the fittest, ” a term that is very familiar to the contemporary ear.

Darwin’s Finches

Perhaps the most significant evidence of natural selection that Darwin found on the Galapagos Islands was in the anatomy of the finches, whose variety piqued his curiosity. Darwin discovered that Galapagos finches have thirteen different kinds of beaks. Through careful observation and consultation with an ornithologist, Darwin began to understand that the difference in the size and shape of the finches’ beaks was due to their adaptation to a particular environmental niche.

Specifically, the different kinds of beaks are adapted to differences in the food supply. For example, in niches where insects are abundant, the finches have developed long, thin beaks which they insert into tree bark in order to extricate their prey. Whereas, in areas where nuts are abundant, the finches’ beaks are shorter and sturdier, allowing the birds to crack the nuts open more easily.

Adaptive Radiation

Adaptive radiation is another example of natural selection at work. Adaptive radiation refers to the process in which a species evolves rapidly to exploit an uninhabited environmental niche. This principle explains some of the variety in physical traits of human beings, even though we are all members of the same species.

Galapagos Marine Iguanas

One of the most interesting examples of adaptive radiation is the case of the Galapagos marine iguanas. The only marine iguanas in the world, they are on almost every island of the archipelago, and number between 200, 000 and 300, 000.

Anthropologists believe that these iguanas arrived on the Galapagos by “island-hopping” from Central American jungles: that is, they floated on rafts of vegetation that drifted through the ocean, eventually ending up 600 miles from the coastline.

Adaptation to their Specific Environment

The food supply is radically different on the Galapagos than in the jungles of Central America, and the only vegetation that the iguanas found on the Galapagos was seaweed and algae, which became the mainstay of their diet.