Thoroughly busts both the myths that birds can't smell, and that they'll abandon the nest if you touch their chicks. A deep dive into fieldwork and preening oil - a lot of the chemistry has promptly evaporated from my brain, but the gist of it remains: the sheer range of variation, and the fascinating linkages with bacteria. The "girl power" chapter bringing together the fact that scents in female birds are clearly important but very understudied, with the fact that female scientists (let alone scientists of colour) are under-represented, was neatly tied together.

Sometimes a bit... not dry exactly because the tone remained conversational throughout, but certainly dense - doesn't underestimate the reader! But for me a good mix of informative and entertaining. ( )

This is the memoir of an ordinary scientist, not one of the superstars rolling in prizes and grant money. As such, I really wanted to like it, and hoped to get a more honest and typical perspective on a scientific life. However, the book was a letdown. In my opinion, the science is not typical. Too much of it is low quality research. There are multiple instances of what seems to be "p-hacking." While it is nice to learn about research in progress, and not only the settled results, I do not have much faith in results that are essentially statistical noise (without significance) or that result from parsing and re-parsing a small dataset to find spurious correlations.

> in birds, only the left ovary develops, which reduces overall body weight

> brown-headed cowbirds smelled like freshly baked sugar cookies! I ran around the lab shoving the poor cowbird in everyone’s faces, demanding that they smell it. (Fun fact: People don’t like it when you thrust a largish songbird in their face, particularly one with a rather strong and pointy beak.)

> I expected that females would prefer the scent of males with more attractive plumage compared to less attractive males. But I was wrong again. Females seemed to prefer the scent of males with less tail white, although the differences between the two choices were not statistically significant.

> In animal behavior, when your predictions are all so spectacularly wrong, it’s time to take a long, hard look at your study and ask yourself what you are really testing. I designed the study with questions about mate choice in mind, but a bird in a plexiglass maze with some scented cotton balls is not choosing a mate. The bird is probably a bit stressed and confused and not interested in sex at all. Perhaps the birds’ choices were related to a different instinct, such as territoriality or fear. I went back and analyzed the characteristics of the males whose scents the females preferred, and I compared them to the rejected scents. Specifically, I compiled data on the males’ tail white (attractiveness), wing length (often used as a proxy for body size), and ratio of body mass to tarsus length (a measure of body condition—basically, how heavy the bird is relative to its body frame). A pattern emerged: whether choosing from within their own population or between their own and a different population, females preferred to be near the scent of smaller males, with shorter wings and lower mass to tarsus ratios. (There was no relationship at all with tail white.)

> Heterozygosity—meaning that the two paired chromosomes, one from each parent, each carry a different variant of a gene—is associated with better overall health. Many detrimental genes are only bad for you when you have two copies of them. Having one functional copy of the gene is sufficient for the body’s needs, and that second, inferior copy will then only be a problem if it is passed on to offspring who don’t get a functional copy from the other parent. Being heterozygous also indicates that there is less inbreeding in your background

> The researchers genotyped the males in their study at several neutral genetic markers called microsatellites (the same markers used in DNA paternity tests). These small, repeating stretches of DNA are commonly used as a proxy for measuring an individual’s overall genetic diversity. Because they are nonfunctional and do not produce any proteins or regulate any other genes, they are free to mutate more often than functional genes, resulting in high variation across individuals

> we found a significant relationship between heterozygosity and preen oil volatile compounds. Specifically, we found that genetic diversity was negatively correlated with the concentration of several volatile compounds, including 1-hexadecanol and 1-heptadecanol. Males with low heterozygosity had more of these compounds in their scent, while males with high heterozygosity had less.

> These results don’t tell us if females used the information present in odor to choose their mates, or if odor influenced whether they mated with an extra-pair male. But they do show that preen-oil-based odor predicts an individual’s potential quality and ability to produce and raise offspring. Testing whether odor alone influences such behavior would require conducting highly controlled experiments, with birds whose odors have been manipulated, and allowing the birds to mate and produce offspring. I haven’t done this work, nor do I currently plan to, mostly because I lack the necessary facilities and resources.

> the evolution of sociality itself could have been spurred by the fact that it increases access to beneficial microbes

> In species with complex social systems, including primates and carnivores, it has been suggested that certain social behaviors like grooming, food sharing, and kissing could have evolved because they transmit microbes. Other researchers have suggested that altruistic behavior—in which one individual helps another, incurring a cost to themselves with no apparent benefit—may have evolved as a way to transmit symbiotic bacteria.

> Unfortunately, my preliminary analysis on the relationship between MHC similarity and extrapair fertilizations in the UCSD and Laguna Mountain juncos is based on some shaky data and would not hold up to peer review at this point.

> Interestingly, the women showed the same preference, although it was not statistically significant.

> after decades of pioneering contributions, Bernice Wenzel sometimes shook her head and remarked how she had felt like a “lone voice in the wilderness” within the ornithological community, which was strongly influenced by the “old boys’ club” of leading ornithologists who were certain they already knew how birds perceived the world. Without diversity in the people who do science, monolithic perspectives can blind us. The fact that women’s discoveries have taken the lead in overturning the long-standing myth of avian anosmia—a myth perpetuated primarily by white men—clearly illustrates this principle ( )