Thread: Evolution of Sense

Of our 5 senses, which one would have evolved first amongst living things? My thought is that touch would be the minimum sensory requirement for an organism to at least be aware of things like temperature, environment, food, possibly itself. Thoughts?

Some form of chemical sensing seems much more plausible. You can't feel a small aggregation of nutritious molecules, but you can 'smell' them.

Originally Posted by John Galt

Some form of chemical sensing seems much more plausible. You can't feel a small aggregation of nutritious molecules, but you can 'smell' them.

I figured chemical sensing would be a more sophisticated sense than touch, more attuned to stalking the prey, an adaptive advantage that develops over time. But if a primitive organism wanted to eat then could it not just ingest everything it touches and expel the waste?

Which 5 senses are you limiting it to?

How do bacteria sized lifeforms sense others? Chemically.

Originally Posted by Neverfly

How do bacteria sized lifeforms sense others? Chemically.

Yes but I'm asking if that would have been the first sense developed by a living organism. Is that what you suspect? I mean would the first living organisms have had any of the five senses when they arrived on the scene? I just think that a life form would have to be able to feel its way around at first. First life wouldn't have much need for scent (chemical tracking) if for instance, they formed at thermal ocean vents when it would be more important to just stay warm. No?

Originally Posted by mat5592

Which 5 senses are you limiting it to?

How many would you like? It doesn't matter since I'm looking for the first to have developed in a living organism. Maybe it's not one of the conventional five, that's fine.

Well, I'm going to have to agree with Neverfly and John, but I don't really have any reasoning beyond what they already said.

Originally Posted by zinjanthropos

Originally Posted by Neverfly

How do bacteria sized lifeforms sense others? Chemically.

Yes but I'm asking if that would have been the first sense developed by a living organism. Is that what you suspect? I mean would the first living organisms have had any of the five senses when they arrived on the scene? I just think that a life form would have to be able to feel its way around at first. First life wouldn't have much need for scent (chemical tracking) if for instance, they formed at thermal ocean vents when it would be more important to just stay warm. No?

I think you are anthropomorphizing the question.

Bacteria "register" or "sense" things around them by basic chemical reactions.

I figured chemical sensing would be a more sophisticated sense than touch, more attuned to stalking the prey, an adaptive advantage that develops over time.

I'd tend to think the opposite (given that I've never once thought about this before today). Sensing predators is more fundamental than sensing prey. You might be able to put up with being hungry just a little bit longer, but avoiding being dead is a top priority all day every day.

Originally Posted by Neverfly

Bacteria "register" or "sense" things around them by basic chemical reactions.

Technically, everything senses its surroundings using "basic chemical reactions", no?

Originally Posted by RedPanda

Originally Posted by Neverfly

Bacteria "register" or "sense" things around them by basic chemical reactions.

Technically, everything senses its surroundings using "basic chemical reactions", no?

Ok, yes. But an issue here is the perceptions of macro vs. micro.
Sight: Chemical reaction of light striking photo-sensitive cells when the photon disrupts an electron
Smell: various different reactions caused by molecules in the air within the sinus
And so on even if others are chemical reactions within the brain, mostly. As in with hearing.

But most readers don't think of sight as a chemical reaction. They think of it as , "It's what my eyes do." Most people routinely consider themseleves to be an individual and not a colony of billions of single cell lifeforms with their own interests in all of this.
When you talk about a bacteria that lacks eyes, it becomes easier to think of the senses as basic chemical reactions 'cuz them lil bugs is kinda stupid.
There is no colony, no brain, no interest except One Base Lifeform involved.

So it makes it easier to think about how it reacts to its environment. After that, it's a matter of scaling back up and seeing the same thing.

In the case of the O.P., the question is what "sense" was first. The only proper answer to such a question, currently, is "Hell if I know."
Because before there were cells, even, was there some kind of sense? Was there any sense that is an approximation of the Common Five?
If a self replicating molecule is impacted by a free agent that assists in replication and division, then that free molecule will chemically react and bind with the proteins that manage the rudimentary DNA molecules replication process. It will be "captured" and "moved into place" even though it was not sighted, flagged for capture, netted, moved with machinery and bolted in. Rather, a "basic chemical reaction" occurred (or a series of them, really) that was the inevitable result of chemistry. Does it count as Sight? Touch? Smell? Do any of those words really apply?
To try to apply any one of those words is to think of the molecule as at least Human... maybe animal... But in the end...
It was a basic chemical reaction.

Originally Posted by adelady

I figured chemical sensing would be a more sophisticated sense than touch, more attuned to stalking the prey, an adaptive advantage that develops over time.

I'd tend to think the opposite (given that I've never once thought about this before today). Sensing predators is more fundamental than sensing prey. You might be able to put up with being hungry just a little bit longer, but avoiding being dead is a top priority all day every day.

I think I have to disagree with you on this one, in that most of our senses serve multiple purposes. For instance the sense of smell can detect both prey and predator, and the same for sight and hearing.

I believe the very first primitive one celled life forms probably only had rudimentary chemical sensing and they survived by replicating themselves faster than the predators that fed on them. As the predator/prey arms race evolved, the cells that had better sensing abilities would live to reproduce more of their kind, so on and so on until the present.

Bear in mind that the threats to the very early lifeforms of Earth were most probably toxins (Or, incompatible chemicals), not predators.

I'm sure most people would agree that the evolution of the vertebrates was a significant chapter in the bio-history book. I've never read about the arrival of a particular sense and the impact it had to have had on animal species. To be able to sense prey or predator surely must have put a tremendous strain on organisms that couldn't and catapult those that could to the top of the survival list. I would think that species either developed or enhanced sense, or else it was the end of the line.

If chemical sensing was first then wouldn't any of the conventional 5 be just more highly evolved packages of the same? If so then the 5 senses are actually one sense with a number of different applications. I can rephrase the OP's question to read: which one of the applications of chemical sensing evolved first amongst living organisms?

Should I know what a plant senses or should flora be excluded from any search for the first chemical sensing by living organisms? I never think of plants being associated with the 5 senses but if chemical sensing is what the focus should be on then perhaps they ought to be included.

I've read that taste and smell evolved/developed first, and then an immune system...All three evolved first merely to best accommodate survival. Interestingly, there was an "over development" of the sense of smell for our early ancestors.

Oops... I read too quickly. You are asking about the first living organisms. I agree with the others...bacteria, algae, etc relied on chemical sensing as they had no formed "senses" as we label them. Multi cellular organisms then started to "sense" light, vibrations, pressure, etc...