Our studies lately have turned toward the incredible variety in the human species. Our scientists considered 31 facial features and the matching genetic codes. You can check out the website we used here.
The list is by no means comprehensive. It does not, for instance, note the variation in prominence or height of cheekbones. Even so, we find a large variation. A chart listing all the potential combinations would need 5,476 boxes.
Now the number cruncher comes out. Our heredity library consists of 23 pairs of chromosomes. That means in the production of a gamete, a parent might have 8,324,608 possible combinations of chromosomes. That is 2 to the 23rd. (We talked about arriving at an approximation in your head. Every 2 to the 10th is about 1,000. So that’s 1,000 x 1,000 x 8.) With two parents, the number comes to 69,299,098,353,664 varieties of person, or about 10,000 times the current world population.
If we throw in the total number of active genes in the human genome – about 20,000 – we arrive at a number large enough to make the universe itself shrink in comparison: roughly 10 to the 12,000th. The observable universe holds 10 to the 80th atoms, give or take a galaxy or two.
That means that if you lived to the end of the universe, you would have far, far, far more chance of hiking across it and picking out a certain atom than of ever meeting someone exactly like you.
Note to twins: Even with the same genetic code, each of you is unique. (But you knew that.) Some "inactive" genes tell other genes when to turn on and when to turn off. One of you might, at adulthood, be able to digest milk. The other may be among the majority for whom the gene for lactose tolerance is turned off.
The list is by no means comprehensive. It does not, for instance, note the variation in prominence or height of cheekbones. Even so, we find a large variation. A chart listing all the potential combinations would need 5,476 boxes.
Now the number cruncher comes out. Our heredity library consists of 23 pairs of chromosomes. That means in the production of a gamete, a parent might have 8,324,608 possible combinations of chromosomes. That is 2 to the 23rd. (We talked about arriving at an approximation in your head. Every 2 to the 10th is about 1,000. So that’s 1,000 x 1,000 x 8.) With two parents, the number comes to 69,299,098,353,664 varieties of person, or about 10,000 times the current world population.
If we throw in the total number of active genes in the human genome – about 20,000 – we arrive at a number large enough to make the universe itself shrink in comparison: roughly 10 to the 12,000th. The observable universe holds 10 to the 80th atoms, give or take a galaxy or two.
That means that if you lived to the end of the universe, you would have far, far, far more chance of hiking across it and picking out a certain atom than of ever meeting someone exactly like you.
Note to twins: Even with the same genetic code, each of you is unique. (But you knew that.) Some "inactive" genes tell other genes when to turn on and when to turn off. One of you might, at adulthood, be able to digest milk. The other may be among the majority for whom the gene for lactose tolerance is turned off.