The mistakes in our genome make a stronger case for evolution than the bits that are right. In essence, a common designer may have designed different creatures with the same "right bits", but why would an intelligent designer have put the same mistakes in two independently designed creatures?

I like the analogy with cheating. If two papers have the same mistakes (misspellings, odd grammatical errors, etc.), it is a pretty safe bet that one was copied from the other or they were both originated from a shared source.

I just finished an interesting article on the gender gap in math. The interesting observation from the article is that there is a correlation between gender equality in a country and having a small gender gap. To the authors, this indicates that the gender gap in mathematics is largely a social construct.

However, the same studies show indication that there may be some biological element involved. Regardless of the gender gap, women do better in reading than in math and men do better in math than in reading. Even more interesting is the data which indicates that women do better in arithmetic than geometry and men do better in geometry than arithmetic.

This implies two things to me. First, cultural factors obviously play a huge role in performance on exams. Having just finished Blink (summary coming soonish), this is no surprise. People are much more influenced by the world around them than they accept. People primed with sentences that include a polite words subsequently act more polite than those primed with sentences that include aggressive words. Black students have been seen to do poorer on exams when they were reminded of their race (e.g., by having to note their race on the exam sheet).

Second, there may be a biological component to gender differences in mathematics. However, if you look more closely, the gender differences are most pronounced within certain parts of mathematics. Thus, it is more relevant to say that "males are better at spatial reasoning" than it is to say that "males are better at math". (I would guess that something similar would be found if one was to do a deeper analysis of the statement "females are better at reading", but I am not familiar with any such work.)

Yet, while this is all interesting, when it comes down to it, I do not think the truth or falsehood of biological differences in aptitude really matters. The current gap in employment of men and women in the STEM fields seems to be overwhelmingly due to the perception of those fields in the eyes of prospective members of those fields.

To take an example from the field I am familiar with, lots of people, both men and women, have no desire to go into CS because of the nerdy stereotype. Now, I work at Google, so I know for a fact that there exist brilliant software engineers who are nerdy and brilliant software engineers that could come across as perfectly normal people; there are people who devote their life to programming, and people who work their days and then go home to be with their families or to swim or to be movie buffs or whatever. There is an attitude in software engineering that you can only be a good software engineer if you dedicate your whole life, body and soul, to programming. This attitude turns good people away from the field.

Until we have addressed the cultural and institutional issues that keep people out of STEM fields, biological differences just do not matter. Their effect is little more than noise in the face of the much larger cultural forces.