When aliens arrive on Earth in their flying saucers, they do so for a reason and intend to abduct people. At least that is what movies and popular social myths convince us. But does it all make sense?

Abduction of humans by aliens
Imagine that you have arrived in another star system, discovered an Earth-like planet, and that it has not only life, but also an advanced alien civilization. What would you do in this case? How about abducting a few dozen aliens and doing something strange with them on board your ship?
At least, according to popular beliefs, this is what aliens who come to our planet do to people. Dozens of movies have been made about this, and many people claim to have experienced something similar.
Of course, there is no scientific evidence that anything like this is happening. The proof of the existence of UFOs was extremely dubious 50 years ago, and it remains so. But let’s imagine that the aliens are us, that we have arrived in the Solar System and seen cities inhabited by some intelligent beings. Does it make sense for us to resort to crime?

Biochemistry and Biology
The first and foremost reason given for alien abductions is biological research. At first glance, this seems logical, but not from the point of view of an evolutionary biologist and ecologist.
Because any intelligent life on the planet is part of the biosphere, and the biosphere is the result of biological evolution. Its source is biochemical processes. Therefore, the basis for studying the biology of intelligent beings is the study of the physical parameters and chemical composition of the atmosphere and hydrosphere. This data is already sufficient in principle to understand the basis of life on the new world.
Further, microorganisms can be obtained from air and water samples, the study of which will already provide more information about the intelligent population of the planet than primitive vivisection. Since the synthesis of proteins based on DNA and RNA in living organisms is essentially the same, the process is not significantly different.

Source: ua.mozaweb.com
In addition, we should not forget about passive surveillance. Flying drones into a forest, coral reef, or savannah and getting information from them about how people move, who eats whom, and how they reproduce is much easier than abducting some drunken native and then having to deal with him when he starts telling you what you did to him.
Then we can take representatives of non-sapient species from nature and study them. This will already provide enough information about the general anatomy of living beings on this planet, and as a result, about the approximate anatomy of representatives of the local civilization. This is called the method of deduction, which is the derivation of individual statements from general ones.
Based on the study of the anatomy of species close to them and simple observations, it is already possible to find out 99 percent of all the information that can be obtained by directly studying the abducted intelligent being.

Books and the Internet
All of the above makes sense only if the alien ship is dealing with a civilization that is at a pre-industrial stage of development. To study the biology of natives with a more advanced civilization, you can use their help.
After all, any advanced civilization must have medicine. And stealing an anatomy textbook and a medical encyclopedia will be much easier and more invisible than stealing a person. After all, who knows their biology better than the locals?
Of course, the language will have to be deciphered, but if you have the time and desire to remain undetected, this is a much more justified practice than abducting people. The library should be one of the first targets for aliens, because it is ready-made knowledge, not only about biology but also about everything that is happening or has happened on the planet. Of course, there may be mistakes in interpreting what is written, but stealing books for aliens is still much more effective than abducting people.

What can we say about the Internet? You can simply connect to it, decrypt it, and you do not need any hijacking at all.
Culture, politics, and volunteers
By the way, if the aliens, which we are, want to interact with the natives in the future in some way other than turning around and flying away, then information about the culture and political realities of the latter will be more important to them than biology. After all, even if it is in your interest to simply destroy your competitors, provoking a world war would be the most effective way to weaken them.
Suppose your plans are more peaceful, for example. In that case, you simply want to turn the planet into your colony, then information about how local culture and politics work becomes vital to you. And again, it is easiest to get this information from publicly available information sources, if they have already appeared on the planet.
And forcibly abducting someone to find out all the clear points is probably the worst way to keep up with all the events. It is much more effective to look for voluntary helpers. After all, if the civilization on the planet has already “grown up” to the idea of the existence of other worlds and life on them, there will be enthusiasts for contact among the population.
And these are the natives who do not need to be abducted. They will voluntarily provide their bodies for the study of everything that is still in question in the field of biology and tell us everything they know about the world around them.

After all, unlike abduction victims, they will not tell you that something strange has happened to them. And finally, assistants can then run errands for you on the planet, search for information, or prepare the ground for contact.
Exotic causes
The abduction of humans by aliens for study for further peaceful contact, conquest, or extermination does not make sense if they have sufficient time and resources for detailed research. It does make sense if the contact is certain to be non-peaceful and very quick.
For example, if some nomadic horde of aliens is planning to pass through the Solar System in the coming decades, and they are going to just eat everything here and fly on, abduction, interrogation, and anatomization may be a strategy. But then there will be no aborigines who return to their people and tell them that they were abducted.
The situation is similar with such exotic possibilities as abducting people for alien zoos, hunting us for food or for ritual purposes, and all that. In these cases, there would simply be no witnesses. At the same time, the scenarios themselves seem somewhat far-fetched.

Source: icantunseethatmovie.com
Finally, if we are to consider all versions, we should not forget about the idea of abduction for mating and hybridizing aliens and natives, no matter how strange it may sound. And this is where abduction is a completely unnecessary thing. This particular task is much easier to accomplish with the help of volunteers.
So in fact, even if aliens are exploring the Earth right now, they are not likely to abduct someone by force and then return them. But they will get collaborators, but the latter will not talk about any violence on their part.
But they will almost certainly tell you how good it is to meet aliens. By the way, there are plenty of such stories, although they are less common than abduction stories. In general, we cannot rule out the possibility that other civilizations have been observing us for centuries, and their methods of obtaining information are so integrated into our society that we simply do not distinguish them from our own culture.