Wednesday, October 30, 2013

Dog, Corn and Almond : how man changed animals and plants to suit him

After you have checked your Facebook news feed, try this one – type ‘Great Dane and Chihuahua comparison’ in Google search. Some nice images will come up. Some sites will even show a side by side comparison, just like they show for mobile phones.
You are in for a surprise. Great Dane is 7 times tall and 20 times heavier than Chihuahua. Usually, they will be considered two species, but they are not. All dogs are same specie.
What do we mean when we say they are the same specie? Two animals are of the same specie when they can interbreed, which means they can mate and produce offspring. But one more condition, the offspring should also be able to produce offspring.
Horse and donkey can mate to produce mule. But mules cannot produce children. Rarely, Lions and Tigers mate to give birth to Ligers and Tigons. But these rare animals are also sterile, meaning they do not reproduce.
But all dogs, however different they might look, can mate and produce pups. So they are all one specie. But then why do they look so different? Not only they look different, they have different qualities. Retrievers can pick up a bird killed by hunter and bring it back to him. Coolies can herd sheep. Some hounds can pick up scent even across running water and after several days.
What created them? The answer is us. We created all these varieties.
Dog is basically wolf. Thousands of years ago, some wolves started lingering close to human sites. Man realized that they are useful animals. Wolves realized that man is useful company. Slowly, the wolves lost the wild characteristics. They became docile. They learned to stare into our eyes – something that very few animals do.
Now man started experimenting. He understood some basic principles of how to breed dogs for certain desired qualities. Armed with these principles, now called Selective Breeding, he created many types, called breeds of dogs.
So what is selective breeding? Suppose the breeders want to create a dog breed with long ears. They take a group of dogs, male and female, with as long ears as they can get. Now when the dogs produce their first pups, breeders select those with longest ears. When the pups grow up, they mate and create a litter. Again repeat the same process. After some generations, you will have a group of dogs with distinctly long ears. Now you have to keep them breeding inside the group. They will be called pure-breed. All you have to do is to give the breed a nice name.
Man used this technique not only with dogs, but many other animals and plants. The almonds found in the wild are bitter. The bitterness comes from a chemical that breaks into cyanide, which as we know, is poisonous. So anybody who is daring (or desperate) enough to make a snack of wild almonds will get very sick, if not die.
But selective breeding created the almonds that we eat. Due to a mistake in genes, some trees of almonds did not have bitter nuts. Some ancient children must have discovered these while they were playing and were hungry. When the elders found out about the edible almond, they used a branch from that tree to cultivate more trees.
Most of our foods are thus modified using selective breeding. The apples in the wild are only one inch in diameter, whereas our supermarket apples are three inches in diameter, nine times as large. The wild corn cob is hardly half an inch long, but we can easily buy a foot long corn cob at our nearest ‘bhuttawala’.
All this happened thousands of years ago. Most of our crops were created between 10,000 years ago and 2000 years ago. Animals were also domesticated around that time. So man moulded the genes are animals and plants without knowing anything about genetics.
The cow can produce around 20 litres of milk everyday, very little of which is needed by the calf. So why does the cow make so much milk? I think you should be able to answer that now.
(In this article, the word ‘man’ is used interchangeably with ‘human’, only for easy reading. No offence meant to women, who played a big role in shaping our foods and animals).

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