We are all aware that adaptative changes take place in living organisms over a long period of time. These changes cause the development of entirely new species from the earlier species. That is the process of Evolution. Let’s take a look at a pictorial representation of the geological time scale
Why is evolution a slow process?
As opposed by “Catastrophists” which say that the process of evolution occurs rapidly, “gradualists” have a different view to this.
Dr. Jean Baptiste Lamarck (French biologist and naturalist) buttressed this fact in 1809 with his explanations based on these two theories:
- Theory of “Use and Disuse”: Which explain the fact that the body part (characteristics) that are being used often tend to be more developed than the parts not used. This also led to the second theory.
- Theory of “Inheritance of acquired trait”: This explains that these changes that occur in individual organisms can be passed on to later generations over time.
When Charles Darwin came on the scene in 1859, he revolutionized biological science, and proposed the theory of Natural Selection in his book “Origin of Species by means of Natural Selection”
May I also remind us that; according to Charles Darwin, life began at the bottom of the sea
That points out to the common ancestry of living organisms.
Proves Of Common Ancestry And Evidence Of Evolution
There are many proves of common ancestry, but I’ll just outline a few.
It is very difficult to trace the precise evidence of the evolutionary trend of living organisms. That could be because; No one lived through history.
But let’s look at this:
- Comparative Embryology: This is a very strong indicator to the fact of common ancestry. Embryos of organisms (vertebrates for example) look very much alike at the earliest stages of development. Even human embryo has tails, gill slits (just like fish) and other comparative features with other embryos.
- Fossil Records (Comparative Paleontology): Fossil evidences have pointed out to the common ancestry of living organisms. This is achieved through the aid of Carbon (radio-isotope) dating.
- Comparative Anatomy: Similarities in anatomy of some groups of organisms suggest common ancestry.
- Biochemical Resemblance
- Macromolecular Records
Is Sickle-Cell Anaemia a proof of Microevolution?
Sickle-cell anaemia, as we all know, is cause by the production of abnormal haemoglobin (S) in lieu of (A). We’re not looking at that aspect, but we’re looking at its relationship with evolution.
According to research, Africa has a greater percentage of population with the “S” trait (not necessarily “SS”, but a trait of it. Could be “AS”)
This is due to the fact that Malaria is prevalent in Africa, and the “S” trait is very resistant to malaria. Now, natural selection will take its action. The mutant ‘S” haemoglobin is naturally selected in the fight against malaria. That is why we have more of these ‘S” traits in Africa. Should I say thanks to Evolution?
With all these evidences of common ancestry and evolution, what is the estimated age of the first appearance of living organisms? Well, no one knows this, but with the evidence from the Last Universal Common Ancestor (LUCA), it should be over 3.8billion years ago (according to research).
It has also been argued that LUCA is not even the earliest form of life.
Believe me, there are more to be discovered in the area of Evolution.
Thanks for reading
Image Sources: 1, 2
References for further reading: Ref1, Ref2, Ref3
