I recently had a discussion with a few colleagues about food additives and there were two major "arguments" about how some of these affect the human body in the long term:

  • some food additives will become less dangerous to humans, they evolve. The same rationale for smoking. The only similar thing I know to support this would be the ability humans gained to drink non-human milk.

  • the first argument is very unlikely to hold because in the vast majority of cases these substances do not affect reproduction and thus people getting sick and/or dying in their 50s+ is not affecting the evolution (food additives and smoking allow one to have children that can reproduce).

Neither of those involved has any in-depth knowledge of how evolution works in these cases and I am wondering if any of these arguments make sense from a biological point of view.

  • 1
    $\begingroup$ This is a really hypothetical question, since it assumes that particular food additives, or the practice of smoking tobacco, will be around for long enough to actually have an evolutionary effect. But most additives have only been around a couple of generations. Even widespread smoking was only around for a century or two. and is in decline most places. $\endgroup$
    – jamesqf
    Commented Jan 15, 2021 at 18:18

2 Answers 2


Evolutionary effects only show up when they have a strong impact on the number of descendants that are produced.

Any disadvantageous effects due to things like food additives and tobacco appear to be quite small with respect to the ability of people to produce children and grandchildren. Moreover, since humans are social animals whose reproductive success is strongly determined by their social relations, there may be all sorts of other effects that interact as well, such as tobacco use being socially desirable or undesirable in particular (sub)cultures.

Thus, there is virtually no chance of evolutionary effects showing up before cultural or technological changes render the issue moot by changing the nature of the environment against which evolution would occur.


Probably not, if for no other reason than tobacco companies and other drug producers have been intentionally breeding their plants to produce stronger and stronger doses of the chemical so that their customers can get a stronger high. It's just another form of biochemical arms race.

As an example, there was once a species of caterpillar that fed on a drug-producing plant, either tobacco, cannabis, or coca, as part of its natural lifecycle, incorporating the toxins into its body. The modern, selectively-bred versions of this plant are so toxic that this caterpillar, which was once specialized to feed on this toxic plant, can't handle it anymore and can only feed on wild, non-cultivated plants. Sadly I have been unable to locate a reference with the exact species.


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