Do things like cells and plants think? How do they know what to do?

I had a thought in my head that has kind of blown my mind. I’m am having a headache trying to figure out exactly how an object like a cell can “know” when to do something. For example, when we are stabbed in the hand with a knife, nerves in our body “know” that something is wrong and “does” something about it by sending a message to our brain.

Wouldn’t the cell have to be conscious in order to do this stuff?, or else how would it know what to do if it can’t think or feel, or smell, taste, hear, see?

I hope this question made sense.

Lacking consciousness, they don’t know what to do. That they exhibit final causality raises the question of how or why they are directed towards a particular end. St. Thomas would say that the Divine Mind directs unconscious matter and the like towards their end. I would like to hear an alternative explanation that does not beg the question.

It’s not a matter of the cell thinking, but of a chemical chain reaction that sends a signal up the nerve.

An analogous chain reaction causes skin damage to spread from a burn site. No thought is involved in that.


With regard to nervous impulses, the impulses they generate travel like the fuse on a firecracker; sodium ions on the outside rush in while potassium ions on the inside rush out. After that zone has passed, molecular pumps re-establish the imbalence, with sodium ions on the outside and potassium ions on the inside.

With regard to cells in general, DNA is unwrapped by certain sorts of ‘zipper’ molecules. The bare strands of unpaired DNA are coded into messenger RNA, which is in turn chopped up and the message ‘translated’ into transfer RNAs in the ribosomes. The transfer RNAs carry amino acids which are used to form proteins in the ribosomes. Proteins carry out carry out enzymatic tasks in the cells, turning oxygen and glucose into carbon dioxide and water while building ATP out of AMP.

It’s all just chemical reactions operating in cycles. The amount of complexity is similar to that found in a desktop computer.

There are thousands and thousands of famous chemical names involved in these things: DNA, mRNA, tRNA, AMP, ATP, chlorophyll, hemoglobin, myosin, cellulose, and on and on. Start here, click the links as you read them, and just keep reading. Do not be put off by your confusion, just keep going even if it makes you dizzy. Eventually it will start to make sense.

With each new link there will be more links. You will be able to read and reread for years to come. Do not limit yourself to Wikipedia; that is just a starting source.

Do not just read, go on youtube and use your new vocabulary to search for videos. Watch the animated molecules in action.

The questions you are asking, if pursued long enough, could see you end up becoming a cell physiologist or biochemist. This line of study could take you through college and on into graduate school, or you might eventually decide to become a doctor.

This could be the first step on a life-long journey.

Frankly, science doesn’t know how cells do a lot of the things they do. Something as simple as the cilia of thousands of epithelial cells working together to move mucus is a mystery. The full function of osteocytes, and **how **they “maintain the bone matrix” is another mystery. How cells control gap junctions is something not fully understood.Things like these are not just a matter of simple “chemical reactions,” and there are many cellular mechanisms which science simply doesn’t understand at present.

From a Catholic perspective: matter is arranged in accordance with the soul, and it is ultimately the soul that is controlling the matter.

Cells function entirely by chemical reactions and physical interactions. No thought is necessary.

By chemical reactions, I mean that molecules join together or break apart, sometimes storing or releasing energy in the process.

By physical interactions, I mean that molecules stick to one another. For example, an enzyme clings to a strand of DNA. The enzyme may promote a specific chemical reaction, like DNA replication. A different enzyme may interact with the DNA and promote a different chemical reaction, like protein synthesis, leaving the DNA intact.

For every interaction that promotes a reaction, there is usually another interaction that inhibits the reaction. For example, a molecule called an inhibitor, if it is present, clings to the replication enzyme and, by virtue of its size and shape, prevents the enzyme from attaching itself to a strand of DNA. Or perhaps a different molecule clings to the DNA and, again by its size and shape, blocks the attachment of a specific enzyme.

So you see that there is a complex system of interactions, and the interactions affect one another, so there are processes that we may call feedback and regulation. This leads to such complex behavior that we may be tempted to think it is directed by some kind of intelligence, but it is really only the marvelous complexity of physical matter and energy.

Plants to not think. Trust me. My wife and I have biology degrees and have been involved with genetic modification of plants for years.

It is chemical reactions you are thinking of.

If you are still fuzzy on the difference I suggest putting down “The Giving Tree” and picking up a biology book.:wink:

Even in our own bodies, complex action does not per se require thought; we do not normally, for example, think about breathing.


I don’t think plants think in the sense than man does. Plants certainly do react to stimuli. But I wouldn’t say that is thinking. That is a more mechanical facility. Aristotelian philosophy considers plants to have a soul. This is the animating principle of the plant. Animals have a soul too with higher powers. Man has a still higher soul with rationality.

There was a recent 2 hour special on PBS on this very topic, they did many various experiments with all kinds of plants flowers, trees, weeds, it was AMAZING how intelligent these living things are, they proved plants/trees of all kinds, have more of an existence than we think.

They have various ways they can sort of call out for help if they need it, protection from bugs, disease, etc. They showed vine type plants can actually sense what direction they need to grow in, based on a few different things, they can actually sense certain things around them, they can even communicate with other plants/trees.

They used a fast forward time lapse video on these experiments to show the plant making choices given to it, I cant tell you how incredible this show was, Im not sure if its online though, I only saw it air once (about 6 months ago).

They also proved plants/ trees can evolve to overcome a threat, they can release toxins if need be, specifically designed to thwart the threat, the show left me wondering if all the trees and other plants are currently developing some method to thwart what mankind is doing to them!!

Cells and human brains both process information and adapt to change in an attempt to maintain homeostasis

Others have already answered.

“how do they do what they do?”

God made it as it is…creation is complex and cool!

Yes. Yes they do. See “The Secret Life of Plants,” by Peter Tompkins and Christopher Bird, published in 1973. It was groundbreaking scientific research. I may become a strict carnivore after reading it, because now I know that plants are sentient beings and I don’t want to eat my friends.

As I recall, one man was able to use telekinesis to communicate with his phildendron and tell it to activate his garage door opener.


I have a climbing rose. It sends long branches 12 or 14 feet into the air. To the north of the rose is a tree to the south is empty space. The rose grows north to the tree instead of south, as it should, to the sun.:confused:

DISCLAIMER: The views and opinions expressed in these forums do not necessarily reflect those of Catholic Answers. For official apologetics resources please visit