But just as all these theories are coming back into vogue at the expense of poor old Darwin, it looks like he's about to be rescued by his old buddies, the finches of the Galapagos Islands. It seems the little rascals went ahead and evolved again, while somebody was watching.
Peter Grant of Princeton Universtiy has been studying the Darwin finches of the Galapagos Islands for decades and had recorded the effects on drought and other environmental changes on the populations. From 1982 until the present, he was able to watch a smaller species of ground finch evolve to cope with the intrustion of a larger species that was in direct competition for its food supply. The larger bird was able to consume the shared food supply at three times the speed of the original inhabitant of this particular island. When a drought hit in 2003 and 2004, further reducing food stocks and increasing competition, the only birds that survived form the island's original population were ones with a smaller beak that could eat a different seed.
They are now the dominant strain of that species because of the mutation that caused them to be born with a different beak. If that second, larger species of finch had never shown up on their island, that mutation would either have made no difference and died out because they could not eat the large seeds easily. Instead they were in a position to survive rather than die out because of their genetic difference.
Natural selection at work - nature chose which was the version of the smaller bird that was more suitable for survival based on the circumstances at the time. A few years from now things may change again and a new mutation might be the one that becomes dominant. There is nothing evil or mysterious about evolution, Darwin, or natural selection. It's happening all the time all around you in many different species.
Most of the time it's far too subtle to make any difference, but sometimes, as in the case of the finchs of the Galapagos Islands, it ensures the survival of a species, in one form or another.
Article comments
1 - duane
Good stuff there, Richard. I didn't miss 10th grade biology, but I've had many, many years to forget it. Thanks for the review. I'm reminded also of how unlikely it is (or was) that birdwatching could have turned into a revolutionary scientific theory.
2 - Serket
I like reading about evolution and have a interest in genetic genealogy. I am probably kind of an anomaly as I am also a non-religious conservative Republican.
3 - duane
Amazingly enough, evolution is not affected by your political leanings or your religious beliefs. Just ask the finches. From the raving, judgmental, fundamentalist finches all the way across the spectrum to the immoral, heartless, godless finches, evolution just keeps on working.
4 - Odin
It's not a huge flaw just a teeny question about adaptations. Obviously they occur, but why? Who or what is responding? Is the response inherent in the genes in the cells of the finch? How do they know how to respond, buried as they are microscopically in the flesh? What overview can they have?
5 - duane
Mutations, as explained in Richard's article. The organisms are imperfect.
6 - Victor Plenty
All organisms are imperfect. Some are more imperfect than others.
7 - duane
Present company excluded, of course.
8 - Odin
Imperfect or not, why the drive to survive? Why don't all organisms just give up under adverse pressures?
9 - duane
The drive to survive? You mean why does it seem like some kinds of trees found in tropical rainforests are compelled to grow tall enough to reach sunlight? Do you think that trees have an inherent survival instinct?
I feel like I'm being maneuvered.
Why don't all organisms just give up under adverse pressures?
By "give up," you make it sound like a matter of choice. You might look up the Arcaca tree to see some adaptive changes under environmental stress, where the stress is provided by giraffes' tongues. I think you will agree that the trees didn't figure this out for themselves.
10 - Victor Plenty
Some individual organisms do give up under adverse pressure. If they give up and die before they have time to reproduce, that particular trait does not get passed on to a new generation.
Whatever genetic combination might produce a "drive to survive," it will be highly likely to spread throughout the population of any species that develops it.
Occasionally a few individuals may lack any form of survival instinct. That makes their branch of the species far more likely to die out. If they die before producing offspring, they don't make any difference to the overall evolution of the species.