I'm designing a "adaptive" humans where repeated physical contact, skin on skin or exchange of bodily fluids, over prolonged period affects the development of the individuals.

The effect I want to achieve is that people who are in extensive physical contact for a quite a long time adapt their physical look and behavior, sort of like the funny pictures where old couples start to look like each other. The change is not very large but it's large enough to be noticeable.

For example imagine a couple that just started dating, where a man is a gym rat who only reads the sports section & woman loves foreign cultures and never lifted anything heavy in her life.

Within a few months man will start to feel strange affection in reading Nepal and woman would't understand how she survived her life so far without going to fitness club. If they broke up the effects will fade in few months, if they stay for a few years the effects will become permanent.

I'm not talking about pretending that you like something, they're starting to really like it.

I want to explain it with some mechanism that already exists in the animal world and could plausibly work on "humans". I know that human semen has antidepressant effect. Ants & Termites use pheromones but that seems far fetched for humans, since they live in colonies. Is there anything similar from our closer relatives where there are two fertile sexes, preferably mammals?

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    $\begingroup$ Pheromones? Just a hint. $\endgroup$ – Mołot Oct 29 '16 at 11:14

AS mentioned, humans are ALREADY affecting their partners with pheromones, or at least the pheromones are enabling an initial attraction to create partnerships in the first place. There is some data suggesting that women can detect incompatible mates and that this mechanism can be blunted by birth control pills so there already exists a mechanism to at least pre-screen mates for certain traits.

Now, how to affect change over time? Secreting hormones that are absorbed by the partner (or anyone in prolonged physical contact) is possible. But it seems unlikely that this could be so specific as to engender a love of cycling or theater. What is more likely is that the effect simply promotes a desire to emulate the other person, what they like you now like. This way you don't need a thousand different hormones to promote a bunch of specific actions, just a generalized effect that has a reliable ability to cause two people to converge in their interests.

If you wanted to get a little crazy, you could have each person affect the other via epigenetics, i.e. up or down regulating gene expression without affecting the DNA itself. So an athletic woman causes her mate to have increased testosterone, which leads to increased athletic performance, for example. But this implies a lot of very selective and specific manipulation for desired traits and seems unlikely.

Anyway, this effect should be limited in range and require prolonged intimate contact. So scent based mode of transmission is probably out, as is sweat based, since handshaking would spread it around. Saliva is a possibility, but if this is really intended for mating pairs, then vaginal secretions and seminal fluid are the best bet. Barrier contraceptives would blunt this effect, but since those are VERY recent technological developments it could have evolved free of such issues. The hormone is secreted and absorbed through the skin (hormones such as estradiol and testosterone are easily absorbed in this manner) during intercourse and then affects the pairs, pulling them together through mutual bonding activities.


The way we as humans perceive reality is subject to constant change, as long as we continue being exposed to new ideas. Now there's a few ways I can think of that would increase the degree to which this is happening:

The first one would be the release of hormones, especially Oxytocin. If your fictional people were to be exposed to higher than normal rates of it, they could willingly become a lot more conformist than is natural. It could be introduced as a socially acceptable drug ("why wouldn't you use this spray, don't you love me???") or even as an engineered "dysfunction" in these humans' bodies (organs overproducing). Check out this study for more info: http://pss.sagepub.com/content/early/2012/09/18/0956797612446026.abstract?rss=1

The other one could be the notion of these people having no real way out of a relationship and being "imprisoned" in it by social/legal frameworks. Under these circumstances, maintaining a working relationship and at least sharing interest in the partners hobbies/passions will be a primary objective of their subconscious. Watch this TED talk starting at 5 minutes and you'll see what I mean: https://www.ted.com/talks/dan_gilbert_asks_why_are_we_happy

By sharing enough interests and conforming to each others respective ways of lifestyle (sports, diet, interest in fashion, etc.) people will automatically also start appearing more similar to one another.


The human body is surrounded by an electromagnetic field, which varies based on mental and emotional activity. It wouldn't be much of a stretch to suppose that when these fields intersect, the more aligned they are, the more pleasurable the experience.

This means that the more two people spend time together, the more they will come to think and feel alike. It wouldn't be instant, because you would need repeated rewards over a period of time to make the new thought or feeling into the dominant one.

The more time two people spent in close physical proximity, the greater the effect would be.

Just as people vary in their conscious awareness of empathy now, you could have individual variation in how adaptable people are to the fields of others. Some people might find a way to block the process completely (especially if they had childhood trauma). They would be effectively blind/deaf in this realm. They might notice the effect happening in other people, and be puzzled about why. People would be uncomfortable around them, because they wouldn't respond, even slightly, to the fields of people around them.

For most people, the process would be completely unconscious, except for some awareness of pleasure/pain when agreeing/disagreeing.

A few might be fully conscious of the process, and may even use it to manipulate others.


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