Expert: Jeffrey Eldred - 6/30/2011

Question
Scenario 1:
Recent studies in various cities have discovered that songbirds are changing the way they chirp and sing in order for them to be able to attract mates. The reason they're doing this is because cities are generally exceptionally noisy with cars, people, machinery, etc.

Is this evolution, or is this adaptation?



Scenario 2:
Recent studies from Canada and Michigan State have discovered that women, when ovulating, have a heightened sense of "gaydar". The reason is because males and females procreate. And (all technicalities aside) a woman can not breed with a gay man. So, ovulating women are able to more accurately distinguish gay men from heterosexual men, thus easily picking out potential mates.

Is this evolution or adaptation?


What is the difference between evolution and adaptation?

Answer
Definitions:
Part of your confusion might be resulting from the fact that there are actually two definitions of "adaption" commonly used in biological science[1] - evolutionary adaptation and physiological adaptation. To say "X (evolutionarily) adapts to Y" is identical to saying "X evolves in response to Y". So "evolutionary adaption" just means any act of evolution in which the reason why evolution occurred is known. Because grammatically, when you use the word adapt, you allude to what a species is (evolutionarily) adapting too.

A physiological adaption occurs when a specific organism responds to something with in its lifetime. That is, it learns something new and changes its behavior as a consequence. This learning can be conscious, such as a human learning a new language when traveling to a different country; Or the learning can be unconscious, such as that human's immune system "learning" how to defend itself against a disease[2], a plant "moving" toward the sun[3][4], or a slime mold "solving" a maze[5][6]. The important thing to understand is that organism aren't born with any physiological adaption and they don't pass on any physiological adaption to their offspring genetically. All physiological adaption takes place within the lifetime of the individual organism.

If I haven't totally confused you yet, the relationship between physiological adaption and evolution can be more complicated. A species can evolve to make certain types of physiological adaption easier. For instance, an opposable thumb and an enlarged brain makes it easier for chimpanzees[7] to use learn how to use tools, but anything that they learn is a physiological adaption. Similarly the ability to acquire language can also be traced to the evolution of our brain, but all languages are adaptions. So sometimes the difference between adaption and evolution is just what aspect is being described, what level of analysis is being performed.


Scenario 1:
I'm not an ornithologist (someone here probably is though [8][9]), but I believe it depends on the bird. A type of bird who is only capable of making a very limited range of sounds wouldn't be able to change its call even if it knew exactly what it wanted it to sound like - then the only way for the bird calls to change would be for the genetic makeup of the bird population to change in response. That would be evolution.

A bird who is capable of making a larger range of sounds, could change its call to better heard by the other birds (but still close enough to the original to be recognized as a mating call). That would be physiological adaption.


Scenario 2:
This is evolution. Or at least a woman's ability to do so in the first place is evolution. Without this evolutionary adaption, she would not be able to distinguish gay men from straight men (as easily) and therefore not be able to react differently. Similarly her ability to recognize gay men from straight men for the evolutionary purpose of producing offspring doesn't necessarily mean that she will actually respond to that knowledge by attempting to procreate with nearest straight male.

The only way this would be an adaption is if the woman actually said to herself "Gee, I'm really in the mood to make babies with someone. I better make sure I focus extra hard on separating the straights from the gays so I can make sure I get it done right." I don't think that's what happened.


A side rant on Evolutionary psychology:
What I discussed in scenario 2 is what confuses a lot of people about evolutionary psychology, - mistaking one level of analysis for another. Most people like hamburgers because they taste good not because they hope they will use the protein to survive in a fight for their life - although the reason meat tastes good to people is that early mankind needed the protein to hunt better. So we have to make sure we don't dismiss an evolutionary mechanism just because it isn't cognitively convincing.

That said, this phenomenon also confuses evolutionary psychologists themselves on occasion, so you have to be critical about it (this study seems okay though). Many evolutionary psychology studies take the form "humans perform strange behavior X; the only reason why humans do X that I can think of is Y; therefore humans evolved to do X because of Y" and it can easily slides into an argument from ignorance[10][11]. To show an evolutionary reason for human behavior, you have to show that there isn't an obvious psychological, cultural, or physiological reason for the behavior. For example, do woman tend to like pink because it subconsciously reminds them of the rosy cheeks of babies, or is it because that every toy they had as a child was pink and they were told they should like it [12]?


Closing:
Since, I am speaking on behalf of All Experts Atheism, I should mention that I think all of this is true independent of whether or not there is a God. And that the existence of physiological adaption does not in anyway mitigate the fact that large scale evolution took place. For this reason, I hope that I explained this all to you correctly and coherently. If you want any further clarification on what I've said or related issues, don't hesitate to ask a follow-up.


Links:
[1] http://encyclopedia2.thefreedictionary.com/Adaptation+%28biology%29
[2] http://www.cdc.gov/vaccines/vac-gen/howvpd.htm
[3] http://en.wikipedia.org/wiki/Phototropism
[4] http://www.youtube.com/watch?v=Ze8NV7cvW8k
[5] http://news.bbc.co.uk/2/hi/science/nature/944790.stm
[6] http://www.youtube.com/watch?v=F3z_mdaQ5ac
[7] http://www.mesacc.edu/dept/d10/asb/origins/hominid_journey/optional3.html
[8] http://en.allexperts.com/q/Birds-General-2349/
[9] http://en.allexperts.com/q/Zoology-1354/
[10] http://www.skepdic.com/ignorance.html
[11] http://wiki.ironchariots.org/index.php?title=God_of_the_gaps
[12] http://www.guardian.co.uk/theguardian/2009/dec/12/pinkstinks-the-power-of-pink