Posts

“Like father, like son”: Testing folk beliefs about heredity in the arena of assisted reproduction.

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“The apple doesn’t fall far from the tree”. “Chip off the old block”. “Cut from the same cloth”. “Black cat, black kitten”. “Chickens don’t make ducks”. “He didn’t lick it off the stones”. “It’s not from the wind she got it”. “She comes by it honestly”.
Every culture seems to have its own phrases describing the power of heredity – not just for physical traits, but also for behavioural ones. (Those last three are peculiar to Ireland, I think). This folk wisdom, accumulated from centuries of observation of human behaviour, seems to reflect a widespread belief that genetic effects on behaviour and personality are strong, indeed dominant over effects of upbringing.
(Image credit: https://schoolworkhelper.net/essay-nature-vs-nurture-or-both/)
Of course, folk wisdom can be wrong. And old folk sayings may not reflect current thinking – perhaps people’s opinions on the subject have changed. Indeed, if you were to take academic discourse on the subject as a barometer of views of the general public, y…

What are the Laws of Biology?

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The reductionist perspective on biology is that it all boils down to physics eventually. That anything that is happening in a living organism can be fully accounted for by an explanation at the level of matter in motion – atoms and molecules moving, exerting forces on each other, bumping into each other, exchanging energy with each other. And, from one vantage point, that is absolutely true – there’s no magic in there, no mystical vital essence – it’s clearly all physical stuff controlled by physical laws.
But that perspective does not provide a sufficient explanation of life. While living things obey the laws of physics, one cannot deduce either their existence or their behaviour from those laws alone. There are some other factors at work – higher-order principles of design and architecture of complex systems, especially ones that are either designed or evolved to produce purposeful behaviour. Living systems are for something – ultimately, they are for replicating themselves, but the…

Debunking the male-female brain mosaic

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There is no such thing as a male brain, or a female brain. Instead, our brains are all really a mosaic of male and female parts – we all have an “intersex” brain. This is the claim made by psychologist Daphna Joel and colleagues, based mostly on a 2015 neuroimaging study in humans, but also some previous work in rodents. This idea – especially the catchy phrasing – has caught the public imagination and it has been widely covered in the media. Indeed, a recent editorial in Scientific American, entitled “The New Science of Sex and Gender”, cited this study as support for the view that “To varying extents, many of us are biological hybrids on a male-female continuum”. But what do the data actually show? I will argue below that the interpretation of a male-female mosaic is conceptually mistaken and based on a straw-man argument. I’ve discussed these findings and their interpretation before, as an illustration of how the same data can be used to support diametrically opposite viewpoints. He…