How do scientists determine the age of a species?

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I was reading in an article that somewhere in Romania they’re trying to save a species of fish that’s 65 million years old. How do they determine that?

In: Biology

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Anonymous 0 Comments

There’s various methods for making that determination, and like all things in science, new information may change the number.

Probably the two most common methods for determining when a species first evolved are using the fossil record and genetic profiling. The fossil record is pretty straight forward. If I find a fossil of a particular species, then I can look at the rocks I found that fossil in and determine how old the rocks are. Once I know how old the rock layer I found the fossil in is, I know that the species has to be at least that old (if it weren’t that old, it couldn’t have wound up in a rock layer that is that old).

Another method is to use genetic profiling. If I can’t find fossils of that species, or I can’t find fossils old enough to determine when they might have first evolved, I might be able to determine what other species it evolved from by analyzing it’s DNA and the DNA of other species. By tracing changes in the DNA of the species I’m trying to date compared to species I know the date of, I can determine things like whether or not one species came from the other, or if they shared a common ancestor (I might even determine that they’re actually the same species with small genetic differences, like different breeds of dogs).

Using DNA in this method is complex. It relies on other information, and the more you learn about a species and the species it’s related to can significantly change your understanding of how those species came about (and therefore, when they came about). So there’s always the possibility that our understanding of when species first evolved could shift. The more information we gather, the better our understanding.

EDIT: I just want to emphasize, these are not the only methods for dating species. Similar to DNA, we can use things like bone structure to understand the relationship between different species and how they may have evolved. And by combining multiple different techniques, we can be more accurate.