Passage A Evolutionary psychology has taught us to examine human behavior from the standpoint of the theory of evolution—to explain a given type of human behavior by examining how it contributes to the reproductive success of individuals exhibiting the behavior, and thereby to the proliferation of the genetic material responsible for causing that behavior.
Passage A
The first paragraph introduces us to the concept of Evolutionary Psychology, which tries to explain behaviors based on how they would have contributed to the reproductive success of the individual behaving that way.
At the end of the 1st, the author asks a Puzzling Question: how can altruism (self-sacrifice) help the reproductive success of an individual?
The 2nd paragraph begins, the answer probably lies in identification / empathy.
So our reading goal is to understand how identification/empathy make it so that altruism helps the reproductive success of an individual. The story seems to be that we can visually identify people who resemble us (and thus who are likely to share some of our genes), and this makes us empathize with them and want to help them more. In the end, I guess the explanation is that we learn to be altruistic to people who look like us, because if they are related to us, then saving them is technically helping the reproductive success of our genes (since they share many of our genes).
The 3rd paragraph is saying that once this mechanism existed (so that we'd be more likely to help our our genetic relatives), it got co-opted more socially within our kin-based groups turned into bigger groups that included non-relatives. Altruism may end up helping strangers in a way that looks "unselfish", but it arose for selfish reasons (trying to save "your genes" by helping someone near you who shared some of your genes).
Passage B
Right away we see there's a Topic Overlap with Evolutionary Psychology. However, this author seems to be against it, not using it. She calls it a "conspiracy theory", which sounds negative.
There's also some saucy attitude in the last sentence of the 1st paragraph: what seemed to be your unsurprising interest in your child's well-being turns out to be your genes' conspiracy to propagate themselves.
The author is saying,
In the 2nd paragraph, the author is providing an example of what she considers to be typical evolutionary psychology -- we have monogamous families (not for the superficial reason of "I found my one true love") because our offspring mature slowly so this type of family improved the reproductive chances of our offspring.
In the 3rd paragraph, the author continues her skepticism of this type of thinking. She feels like evolutionary psychologists are forcing everything through their explanatory lens, when there are other, possibly simpler and more intuitive ways to explain some forms of behavior.
She seems convinced that some of our behaviors are not controlled by genetic interests; they're just products of our own curious free will.
Overlap
Both passages deal with evolutionary psychology and with altruism.
Passage A presents how evolutionary psychology would explain altruism. Passage B alludes to it very vaguely at the end of its 3rd paragraph.
Divergence
Passage A seems to like / trust evolutionary psychology, whereas Psg B seems a little annoyed that evolutionary psychology insists on thinking that every single thing has an evolutionary explanation.