20061009 - No Ma'am
This is completely out of context and I have no references other than "I was watching PBS this evening and I heard them say..." However, it's so compelling, that I figured if anyone really wanted, I could look for a list of appropriate references that could explain this much better than I can here.

While watching some nature program on dolphins and whales on PBS this evening, something near the end of the show really caught my attention. It had to do with a difference between the males and females of the particular species they were talking about off the coast of Seattle, Washington, USA.

The narrator was talking about how he was so shocked about how many of the males of the species he recalled filming in the 1980s were gone. As he conversed with the scientists whom are currently studying these particular organisms, they told him why specifically it was that the males had decreased so sharply.

The reason they gave was toxins in the water (I don't recall exactly where the toxins came from or how they got in the water or whether it had to do with eating other organisms or just a matter of being in the water).

Naturally, the question arose, "Why so many males gone, but not as many females?".
They explained that the females were able to expel much of the toxins out through their milk. It meant that their offspring would usually die, but at least the mother would survive.

They did not dwell any longer on the topic, but just left it at that and the show ended pretty much on that note.

So, why do I have this story in my "Interesting Facts about Evolution" section?
Before I answer that question, I'll ask another...  It would seem counterproductive to put toxic material in the food of the very offspring which would need to survive in order for the species to pass on its genes to another generation. So, if evolution works by way of accidental genetic mutations resulting in anatomical changes which either help or hinder an organism's survival in a given environment, then what part of dispensing toxins out through one's mammary glands would be helpful here?

Well, which came first; the mammary glands or the toxic pollution in the water of these particular organisms? To get further down to the real issue here, we must deal with the issue of the evolutionary process in general as well as the evolutionary history of the mammary glands them selves specifically.

Once again, evolution doesn't happen in direct reaction to the environment, as if an organism just up and changes it's genetic makeup to somehow match some change in the environment.
It happens by way of (as just mentioned above) accidental genetic mutations which accumulate over time.

However, individual genetic mutations along the way do not usually necessarily cause any noticeable anatomical change in an organism such that they immediately become more capable of dealing with or able to thrive in their present environment.

Rather, in situations where a genetic mutation does eventually result in what we'd recognize as an evolutionary change, the individual mutations accumulate over time and lead to anatomical changes which aren't usually 'noticeable' until some extreme change arises in the environment.

In this case, the females had previously evolved mammary glands before this particular environmental change whereas the males did not. When the environment changed (us spilling toxic chemicals into the water where they live), the females fared better due to not only having mammary glands but also this tendency to expel toxins out through them.

That's where we ask, "Well, where did mammary glands come from?"
It just so happens to be that mammary glands in females (where breast milk comes from) evolved from sweat glands somewhere along the way in the evolution of mammals (named after these specialized glands).

Yep, a gland which is now involved with producing substances which are usually nourishing (and in some cases, essential) for offspring to consume in their growing process after being born evolved from a gland which the body uses to expel toxins out through the skin (of course, the sweat gland also served to help the mammal in its bodily temperature regulation system).

When we consider the evolutionary history of the mammary gland, it's not so odd to see this situation in this particular whale species. The fact that the females' survival rate is better than that of males is simply an accidental result of an accidental tendency to expel toxins out through certain glands which evolved accidentally via genetic mutations somewhere along the way.

So, why have the males of the species died off so much more drastically than the females?
The shortest answer I can come up with is, "No ma'am".

Of course, my main interest is in studying the evolution of my own species, Homo Sapiens 

back to my home page    contact me    .    .    .