Although the latest published result of the study appears in this month’s issue of the journal Genetics, the study itself began in 1972. Researchers in Novosibirsk, Russia, captured a large group of wild rats, then split the group at random into two lab groups. One was arbitrarily (at first) labeled “tame”; the other, “aggressive.”
It seems the researchers are assuming that tameness does have a genetic basis, in which case their logic of breeding and genetic comparisons stands up.
Over the years, the scientists have continued to breed two new generations per year in each group. In the tame group, the friendliest rats are bred together; in the aggressive group, the meanest rats are bred together, resulting in two very different rat groups. LiveScience reporter Jeanna Bryner explains how differently the rats react to humans:
Demeanor in rats is tested with the glove test, in which a human hand protected by a metal glove approaches a caged rat. The tame rats tolerate the hand and even sometimes toddle across it. Aggressive rats try to escape, scream, attack and bite the person’s hand. The rats even perform boxing moves, standing on their hind legs while sort of punching the human hand away.
To move the study forward, the researchers created a third group by breeding some of the tamest rats with some of the most aggressive; their offspring were then interbred again. The researchers then examined the genes of pairs of rats pulled from this group that were not as tame as each other. Any genes that were identical could be ruled out as causing the difference. Likewise, any two rats that were equally tame could have their differing genes ruled out. The result is identification of “sets of genes” that could be responsible for tameness.
“I hope our study will ultimately lead to a detailed understanding of the genetics and biology of tameness,” said Frank Albert of the Max Planck Institute for Evolutionary Anthropology. “If you think about dogs, they are such amazing animals. When you compare a dog with a wild wolf, a wolf has no interest in communicating [with] or tolerating humans. If you’re lucky a wolf in the wild wouldn’t care about you. But a dog does care and they even seek human presence. Dogs were all wolves at some point. How did they become these animals that need humans to exist?”
One caveat on the research: it seems the researchers are assuming that tameness does have a genetic basis, in which case their logic of breeding and genetic comparisons stands up. However, if tameness were due to epigenetic factors (for example, somehow connected with the interactions of a rat’s mother while the rat is in utero), then the sets of genes identified may not code for tameness at all.
But if there is a genetic basis for tameness, this would help us understand another factor that has increased biodiversity since the animals departed from the Ark. After all, as Albert points out, there is a significant discrepancy between not only the size, color, coat, etc., of dogs and wolves, but also between their respective behavior. Both may be understood through such factors as artificial and natural selection acting on inherited variations, including (possibly) tameness.
Ultimately, we know that the original animal kinds were created without the fear of man, which only came after the Flood (Genesis 9:2). That surely helped as Adam named the animals on Day 6 of Creation Week (Genesis 2:19–20)!
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