Wikipedia:Reference desk/Archives/Science/2022 September 12

= September 12 =

How many food calories does an ant or roach need per day?
In insects is fat still worth 9/4ths the energy of sugar, starch and protein? Only then would it make sense to use calories as a unit of accounting (though "minimum calories per day per tonne of adult organisms to prevent hunger" probably differs from humans). And how many nanograms are in each of the sugar (or are they cream?) particles that appear as dense as helium when you try to get all the electrostatically attracted particles out of a peaches and cream oatmeal packet? I've always wondered how many of these rising grains the smallest common newborn house ants and roaches would need to eat each day and if they're able to eat them the same way they eat larger crumbs. How small can a microcrumb be before the tiny ant or roach either can't see the crumb with it's crappy compound eyes anymore or it starts getting difficulties with transporting the crumb from ground to stomach? Sagittarian Milky Way (talk) 14:12, 12 September 2022 (UTC)
 * Although I have heard that in many insect species, including some ants, the adults don't bother eating, one can estimate the maintenance calorie requirements for any lifeform using their mass and Q10 (temperature coefficient). Abductive  (reasoning) 23:49, 12 September 2022 (UTC)
 * Q10 is a dimensionless quantity and mass has dimension M, while calories are measured in joules, with dimension M(L/T)2. Dimensional analysis implies one cannot infer a need per time unit without an additional input whose dimension involves L, (next to possibly M and T, but nothing else). One might hope to use an organism's density. --Lambiam 10:46, 13 September 2022 (UTC)
 * If you look around in the article, you'll see that for "most biological systems, the Q10 value is ~ 2 to 3". Abductive  (reasoning) 20:28, 13 September 2022 (UTC)
 * So? Can you show us how one can use this information to estimate the maintenance calorie requirements for a lifeform whose mass is 1 kg? --Lambiam 22:18, 13 September 2022 (UTC)
 * Sure. The average adult human female needs 2000 kilocalories a day to maintain her 53 kg mass and her 37°C temperature. Each 10°C drop cuts the calorie need roughly in half. So a 1 kg organism at 37°C would need ~38 kcal (2000/53), an ectotherm (or a hummingbird in torpor) at 27°C would need 2–3 times less than that, and a fish at 4°C would need less than 4 kcal. Abductive  (reasoning) 03:56, 14 September 2022 (UTC)
 * So a 1 milligram insect (~1mm3, slightly less than the average I've found for the weight of a very young house roach from a small species) would need about 13-19 microCalories at 27°C? Or 3 to 5 micrograms of dry carbs and/or proteins per day. A Google search says an ant eats up to a third of it's body weight in a day though, even if the food was watermelon that seems like a lot. Sagittarian Milky Way (talk) 05:13, 14 September 2022 (UTC)
 * One has to be careful when considering organisms that are growing or making eggs, those costs are commonly given as 10:1—they have to eat 10 times a unit of food to create one unit of themselves. Abductive  (reasoning) 11:08, 14 September 2022 (UTC)
 * Would the little newborn insect just not grow if only given enough to not lose weight? (or actually for ants the smallest ~1 milligram ants you see are not newborn or the smallest, which would be larvae, with roaches they crawl right out of the egg so you can see them without needing to see their secret hiding place) Sagittarian Milky Way (talk) 14:26, 14 September 2022 (UTC)
 * In fruit flies, at least, the larvae continue to try to develop, and depending on how little food there is, come out really small. But there is a lower limit. I seem to recall hearing that some organisms can put off development in a sort of torpor for a considerable period of time. Abductive  (reasoning) 00:51, 15 September 2022 (UTC)
 * This is based on the assumption that the metabolic rate of all these lifeforms for a given temperature is roughly in the same range as that of an adult human female. The data for the female amount to 37 kcal/kg/day. Sources give 1600 kcal for a sedentary female, which lowers the basal metabolic rate to just 30 kcal/kg/day. For hummingbirds, I find the value of 1,600 kcal/kg/day, almost two orders of magnitude larger. --Lambiam 09:57, 14 September 2022 (UTC)
 * These are all estimates that one can then use to compare species and find outliers, such as hummingbirds, which are up to no good. Remember that a calorie is the amount of heat required to raise the temperature of a gram of water 1°C, so the 2000 kilocalories you ate today could raise a gram of your water to 2,000,037°C.  Abductive  (reasoning) 10:55, 14 September 2022 (UTC)
 * I heard that apples-to-apples animals need to eat more of their body weight per day for physics reasons. Or is that only for warm-blooded animals? Sagittarian Milky Way (talk) 14:28, 14 September 2022 (UTC)
 * An adult alligator and an average adult dog need approximately the same calories per day. Many organisms, particularly ones like snakes that don't expect to eat every day, have a variety of energy-saving adaptations. It is thought that warm-blooded animals have fewer such adaptations because the need to eat so much and the warm-bloodedness are inter-related. Animals such as cave fish have pared down their energy-gobbling tissues such as liver and kidney to astoundingly low levels, and can get by on eating, like, one Daphnia a week. There is tremendous selection pressure for saving energy, but a countervailing pressure to quickly obtain nutrients to grow faster and to make babies faster. Exploring the energy usage of various organisms provides insight into these evolutionary history of the organisms. Abductive  (reasoning) 00:51, 15 September 2022 (UTC)


 * Basal metabolic rate is definitely the article where one could hope to find that sort of information, but it has no values for non-human animals. Hence we turn to a general online search with the appropriate keyword, and one finds this article for ants (the non-paywalled abstract has values) and that for roaches. (One also finds this, but the "Journal of Fish Biology" is a hint that we are talking about another kind of roach).
 * The values are given in the rate of O2 consumption normalized by the mass of the animal, but I cannot be bothered to the conversion to calories per day for standard-size insects is left as an exercise to the reader. The reader is also cautioned that Temperature is the most important determinant of metabolic rate in ectothermic animals (first sentence of the roach paper). Tigraan Click here for my talk page ("private" contact) 16:20, 13 September 2022 (UTC)

IQ and life age
Is there any scientific evidence that IQ remains constant over a person's lifetime? 2A02:908:424:9D60:0:0:0:4A03 (talk) 17:04, 12 September 2022 (UTC)
 * What leads you to believe that it does? ←Baseball Bugs What's up, Doc? carrots→ 18:19, 12 September 2022 (UTC)
 * What leads you to assume that the questioner believes it does? --Lambiam 22:27, 12 September 2022 (UTC)
 * Because he asked. Keep in mind this is the same IP that recently asked whether empathy is a "finite resource". ←Baseball Bugs What's up, Doc? carrots→ 01:30, 13 September 2022 (UTC)
 * Huh, to me a question of the form “is there any scientific evidence that X” suggests skepticism about X, not an assumption of its truth. —Tamfang (talk) 03:14, 13 September 2022 (UTC)
 * Maybe the IP will explain, in 8 or 10 days. ←Baseball Bugs What's up, Doc? carrots→ 05:11, 13 September 2022 (UTC)
 * I have read this claim a looong time ago. 2A02:908:424:9D60:0:0:0:4A03 (talk) 16:11, 13 September 2022 (UTC)
 * What do you assume about me because of this question? 2A02:908:424:9D60:0:0:0:4A03 (talk) 16:09, 13 September 2022 (UTC)


 * Some general articles:
 * Is Your IQ Fixed For Life?
 * Why IQ Fluctuates Over Your Lifespan
 * Does IQ (Intelligence quotient) of a person change with time?''
 * Alansplodge (talk) 18:33, 12 September 2022 (UTC)


 * The bottom line is that as we get older, we get better at taking IQ tests. ←Baseball Bugs What's up, Doc? carrots→ 21:07, 12 September 2022 (UTC)
 * Unless and until disease, disorder, or damage causes an impairment in brain function. --User:Khajidha (talk) (contributions) 00:26, 13 September 2022 (UTC)
 * Yes. That would affect most everything, not just the ability to take IQ tests. ←Baseball Bugs What's up, Doc? carrots→ 01:32, 13 September 2022 (UTC)
 * The table shown here suggests a trend of decline with age. However, it is synchronic, so one cannot conclude anything for the trend line of people as they age. If individual people's IQ does not tend to decline, the decline in the table date implies an increase in successive cohorts taken at the same age. Tests on the market are regularly recalibrated to give a population average of 100. Therefore, comparing tests results taken at different moments in time is only meaningful when reusing the same test. --Lambiam 10:30, 13 September 2022 (UTC)
 * That single page sums it up nicely. The abilities by which intelligence is measured do in fact decline steadily after around 30 years of age, but IQ is defined in a way that the mean is 100 at any age. So to answer the OP's question, intelligence declines with age, IQ does not. nagualdesign 19:23, 13 September 2022 (UTC)
 * We cannot draw this conclusion from the data in the table. It is a snapshot, one still from a movie, not enough to recreate the movie. --Lambiam 21:58, 13 September 2022 (UTC)
 * I'll let myself add a few words after the bottom line. Perhaps the IQ stays the same as a person ages, but intelligence need not drop. If you keep an active mind and body throughout your long life, then You're still very well in the moment after ninety or one hundred. --Ouro (blah blah) 07:28, 14 September 2022 (UTC)
 * The issue that everyone seems to be confusing here is the difference between averages and specific individuals. WHATEVER the actual average trend is for intelligence over time; that any ONE person will actually follow that trend is unknown.  It is likely they will, but it is also possible that YOU may follow a different trend.  Just because something happens on average doesn't mean it will happen in an identical way for one person.  -- Jayron 32 12:15, 16 September 2022 (UTC)