Sharky genes reported in ABC News in Science 30 May 2007.
Researchers at the Institute of Molecular and Cell Biology, Singapore, have studied gene sequence sin the elephant sharks, bony fish, chickens, mice, dogs and humans. They found 154 genes in humans that could be matched to genes in sharks, mice and dogs. The researchers expected to find similarities between humans, mice and dogs because they are all mammals, but elephant sharks are a long way from people on the evolutionary tree.
Furthermore, humans and sharks had more in common than humans and bony fish. Byrappa Venkat, who led the study commented, “This was a surprising finding, since teleost (bony) fish and humans are more closely related than the elephant shark is to humans.”
However, experts in shark biology are not so surprised because humans and sharks have some physiological processes in common that are not found in bony fish. For example, sharks have internal fertilisation so their sperm have a receptor in the tip that enables them to combine with the female egg cell. Bony fish sperm don’t have these receptors because they enter egg through a pore that humans and sharks don’t have.
Sean Van Sommeran, executive director of the Pelagic Shark Research Foundation in California, says that he was not entirely surprised to learn about the shark-human similarities. He commented, “Sharks copulate like mammals and females give birth to live young, so sharks do have features in common with mammals. It makes sense that these would show up in the genome.”
Editorial Comment: It is good to see someone talking common sense about genome studies. If two living things have some similar structure, such as the sperm receptors they would be expected to both have the genes needed for making it. This does not prove one organism evolved into another, particularly when the supposed intermediate forms don’t have the genes, but it does fit with the separate creation of things which have similar functions. If the creator wanted two living things to carry out some function in a similar way he would give them both the same genes, even if he gave them many other different functions.
Evidence News 13 June 2007