Raising a child costs 13 million calories

That’s right. Somebody actually did the math on that. Kaplan in 1994, to be exact.

The anthropologist and his colleague, Kate Kopischke, looked at how three semi-isolated populations from South America live. Between September 1988 and May 1989, the researchers analyzed several variables meant to shed light mainly on fertility rate and wealth flow. They measured the amount of time spent taking care of children. They estimated the best time to have a second child. They weighed the food of these communities. And then they estimated the caloric intake and expenditure per day per individual.

Human children are unable to provision for themselves until about the age of 18. So most of their caloric intake requirements are provided by their parents. Long story (39 pages) short, Kaplan (1994) concluded that a child relies on 13 million calories provided by the adults. Granted, these are mostly hunter-gatherer communities, so the number may be a bit off from your average American child. The question is: which way? Do American kids “cost” more or less?

143 13 mil calories - Copy

P.S. I was reading a paper, Kohl (2018), in the last week’s issue of Science that quoted this number, 13 million. When I went to the cited source, Hrdy (2016), that one was citing yet another one, the above-mentioned Kaplan (1994) paper. Luckily for Kohl, Hrdy cited Kaplan correctly. But I must tell you from my own experience, half of the time when people cite other people citing other people citing original research, they are wrong. Meaning that somewhere in the chain somebody got it wrong or twisted the original research finding for their purposes. Half of the time, I tell you. People don’t go for the original material because it can be a hassle to dig it out, or it’s hard to read, or because citing a more recent paper looks better in the review process. But that comes to the risk of being flat wrong. The moral: always, always, go for the source material.

P.P.S. To be clear, I’m not accusing Kohl of not reading Kaplan because accusing an academic of citing without reading or being unfamiliar with seminal research in their field (that is, seminal in somebody else’s opinion) is a tremendous insult not be wielded lightly by bystanders but to be viciously used only for in-house fights on a regular basis. No. I’m saying that Kohl got that number second-hand and that’s frowned upon. The moral: always, always, go for the source material. I can’t emphasize this enough.

P.P.P..S. Ah, forget it. P.S. 3. Upon reading my blog, my significant other’s first question was: “Well, how much is that in potatoes?” I had to do the math on a Post-It and the answer is: 50,288 large skinless potatoes, boiled without salt. That’s 15,116 Kg of potatoes, more than 15 metric tones. Here you go. Happy now? Why are we talking about potatoes?! No, I don’t know how many potatoes would fit into a house. Jeez!

REFERENCE: Kaplan, H. (Dec. 1994). Evolutionary and Wealth Flows Theories of Fertility: Empirical Tests and New Models. Population and Development Review, Vol. 20, No. 4, pp. 753-791. DOI: 10.2307/2137661. ARTICLE

By Neuronicus, 22 October 2018

Tryptophan-rich foods and happiness

angry-woman public domainThe paper I feature today is not an experimental study, but an editorial written as a short review (5 pages). A not very good one, I’m afraid.

Neurochemical imbalances are to be found in virtual any brain disorder. Probably the most known is the serotonin depletion associated to depression, which is the main reason why SSRIs (selective serotonin reuptake inhibitors) are so widely prescribed for the disorder. With the caveats that serotonin is but one player, that it has many receptors involved in different aspects of the disease and “depression” is an umbrella term for a host of behaviors, this editorial focuses on non-pharmacological ways to address the depletion of serotonin. Noble goal, poor execution.

In a nutshell, Young (2007) argues that there are 4 ways to increase serotonin availability in the brain:
1) effortful focusing on positive things, either via psychotherapy, talk, social interactions, mediation or just mental exercises to consciously improve mood. I’m sure that the thought of trying to focus on the positive thoughts never crossed the minds of depressed people! Of course that this is how healthy people regulate their moods, everybody is sad or suffers loss at some point in their life and a lot of people snap out of it by engaging in those suggested behaviors, but the trouble with depression is that it persists despite efforts to be positive. The author should know that crying “Cheer up!” to a depressed person never works, but chances are they would feel even more alienated because they’ve tried that already!
2) exposure to bright light (3000 lux). No contention here. Light therapy is successful in treating seasonal depression. We should all get more light.
3) exercise. It’s unclear which kind, aerobic or to fatigue, but probably either would work.
4) eating tryptophan-rich foods (like meat, cheeses or eggs). Why tryptophan? Because the brain can make serotonin out of tryptophan, but serotonin itself is too big of a molecule to enter the brain (i.e. doesn’t cross the brain blood barrier). But the author admits that “although purified tryptophan increases brain serotonin, foods containing tryptophan do not” (p. 396) soooo,… then eating tryptophan-rich foods will NOT increase the serotonin. But then he goes on saying that drinking milk or eating nixtamalized corn increases serotonin (verbatim: “Acute ingestion of alpha-lactalbumin by humans can improve mood and cognition in some circumstances, presumably owing to increased serotonin” and “Breeding corn with a higher tryptophan content was shown in the 1980s to prevent pellagra; presumably, it also raised brain serotonin” p. 396-397). Utterly confusing and self-contradictory.

I also want to make a big note here:
a) there is no reliable evidence that eating tryptophan-rich foods increases the brain serotonin. Otherwise, instead of paying for Prozac, you would buy a huge bottle of tryptophan pills from the nearest dietary supplements store. Which brings me to my second point:
b) why don’t we give tryptophan supplements instead of SSRIs? Tryptophan is sold in USA as a dietary supplement which I think is a tremendously dangerous thing to allow (in most EU countries is considered a drug, so you can’t buy it from the shoddy dietary supplements stores). Because its efficacy in depression is inconclusive at best, i.e. most studies did not find significant improvements, while others showed improvement only in a subpopulation of depression sufferers. But it can induce nausea, sleepiness, confusion, depression, and even dementia symptoms and death. And interacts badly with other drugs or even with carbohydrate-rich foods, like pizza or pasta.

This is definitely not among the best papers I have read. It has many speculations supported by un-replicated studies. Or, when such studies are sparse, the reasoning relies on evolutionary speculations elevated to the rank of causal explanations (e.g. we spend so much time indoors, therefore depression is on the rise; conversely, our ancestors spent more time outside, therefore they were happier). Although I agree with Young that we should invest more research into non-pharmacological ways to improve brain dysfunctions, we need to do so in a more pragmatical manner that just telling people to think positive. Ok, rant over.

Reference: Young SN (Nov 2007). How to increase serotonin in the human brain without drugs. Journal of Psychiatry and Neuroscience, 32(6):394-399. PMID:18043762, PMCID:PMC2077351. Article | FREE FULLTEXT PDF

By Neuronicus, 3 December 2015