Cattle are selectively bred to encourage characteristics that the breeder wants to enhance. These might include greater muscle mass, thicker fur for survival in colder conditions or higher milk production. In the case of the Belgian Blue cattle in the following video the breeder is trying to enhance ‘double muscle’ to produce cattle for showing at competitions and exhibitions.
The Belgian scientist does refer to what he is doing as natural selection (2.45) but it is very much artificial selection or selective breeding. The reason that such dramatic changes can be achieved in so short a time is that the researchers bypass nature and make the key decisions themselves. In natural selection, fitness to survive and pass on your genes is not necessarily about being the biggest or the strongest. Selection using artificial insemination takes the process one stage further.
They also talk about a single gene being responsible for growth regulation. I think that most genetic researchers would now agree that the idea that everything is about single genes is too much of a simplification. A gene is the code necessary to produce a single protein; humans have about 20,000 protein coding regions on our DNA. It is likely that more than one gene is involved in muscle growth and that its expression will in turn be controlled by other factors – what is known as junk DNA. Most of the DNA in your cells does not code for genes and this non-coding material was termed junk DNA. It now seems that it does often serve a purpose even if that purpose is a little more subtle than merely being the code to produce a protein.
The second video is about research into how humans domesticated dogs from wolves – using wild Arctic foxes as the test subjects. I found it very interesting but it does include scenes with dozens of foxes in quite small cages. If like me you are a fan of dogs you might get the urge to liberate them all! Science research often has uncomfortable consequences but I think that what is being learned here is of genuine interest. You may want to disagree, and tell me why, in the comments section below.
Questions…
- What is the mammalian male gamete called?
- What name is given to the cell formed when a male and female gamete nucleus fuse?
- Suggest a feature that shows a Belgian Blue is a mammal?
- For what does a gene code?
- What nickname is given to the non-coding parts of your DNA?
- Is milk production in cows a continuous or discontinuous characteristic?
- Is milk production the result of genetics, environment or both? Explain your answer.
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