QUESTION 25: HOW MANY GENES DOES A HUMAN HAVE?

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Until the 1990s, the idea generally accepted by the scientific community was that in the genome of any human could be on the order of 100,000 genes. But as the Human Genome Project was shedding light on our DNA sequence, that number went down. Thus, when in the year 2000 the scientific parents of the Project together with politicians Bill Clinton and Tony Blair presented the first draft of the human genome, the estimate lowered the number of genes to 25,000-30,000. But that draft was only the beginning. Since then we have been working on the huge amount of information obtained and the latest estimates put the number of genes present in each of our nucleated cells in about 20,500.

The next question that should be asked is, are these few or many compared to other living organisms? And the answer can not be any other: they are, exactly, the ones we need. Sometimes - too often - journalists and scientists often play to confront the number of genes, the size of the genome, the number of chromosomes, the similarity between DNA and other characteristics linked to our genetic material with that of some animals for arrive to really absurd situations. And it would be as if knowing that the number of pieces that have a computer we ask ourselves if they are few or many compared to other elements like a motorcycle, a toaster or a mechano. The conclusion we could reach would be as ridiculous as it was meaningless. DNA is the same.

However, in order to satisfy the curiosity of those who may still have it and without the intention of entering into comparisons that we have already said that they can not do, I will show in the following table the number of genes of some species more or less distant from ours.

Species                                                    No. genes
Human being (Homo sapiens)                 20,500
Water flea (Daphnia pulex)                     31,000
Mouse (Mus musculus)                           23,000
Bacteria E. coli                                          4,377
Rice (Oryza sativa)                                  28,000
Yeast (S. cerevisiae)                                  5,800
Fly (Drosophila melanogaster)                17,000
Worm (C. elegans)                                   21,733
Arabidopsis (A. thaliana)                         25,500
Dog (Canis lupus)                                    19,300
Mycoplasma genitalium                               485
EBV virus, which causes mononucleosis      80