Several issues in evolutionary biology have remained controversial for decades:
1) Why do most organisms grow old and die, while some (e.g., hydra) are immortal?
2) Why do so many organisms engage in sexual reproduction when asexual reproduction has the advantage of passing on ALL of one's genes to the next generation?
3) Is the individual the only important unit of selection, or does group selection play an important role in evolution?
Perhaps we can learn something from this little fish. Because according to the article below, high mutation rates in asexually reproducing human mitochrondria could lead to our species' extinction.
So do these mutations even exist? No-one, to my knowledge, has actually shown this, or is in any position to do so. If they exist at all, there is the further question of how many of them there potentially are, which again has not been answered.
You do not believe that the accumulation of deleterious mutations is a disadvantage of asexual reproduction? What do you see as the advantages of sexual reproduction (other than the fact that it's fun :-) )?
Edited by Stephen Push, : Rephrased second question.
Well, it's useful. In order to be able to plan ahead, we have to be able to say to ourselves: "What would happen if I do such-and-such a thing?"
Intuitively I agree with this account of the value of imagination. But as a scientific explanation it seems problematic because it presupposes the existence of free will, a property that appears to defy scientific analysis. Is there any way to establish that free will actually exists, not to mention how it could have evolved?
Well, it's useful. In order to be able to plan ahead, we have to be able to say to ourselves: "What would happen if I do such-and-such a thing?"
By way of suggesting a practical value of imagination, you seem to be describing a conversation with yourself in which you choose from two or more options. That seems to suggest the exercise of free will. Unless this internal conversation is just an illusion without effect on the outcome. But if so, where is the practical value?
And so, so long as I make superior non-choices with an imagination than without one, which I think is beyond doubt, then it is biologically advantageous to possess the faculty.
And so, so long as I make superior non-choices with an imagination than without one, which I think is beyond doubt, then it is biologically advantageous to possess the faculty.
While we can't rule out the possibility that the particular crow in the video learned to use cars as nutcrackers, anecdotal evidence can be misleading. In the study, reasearchers did 231 paired observations of crows with and without cars approaching. The crows were no more likely to drop walnuts on the road if cars were approaching than if cars were not approaching.
Dude, crows are smart. Like way smart. Check out this one make a hook:
Yes, tool use in crows is well documented.
Well, they're not unconscious (unless they're sleeping).
A better word for what I think you're talking about would be sentient, no?
Definitions are part of the problem. Researchers in this field often have different definitions of what they mean by consciousness. We don't even understand consciousness in humans, so it's probably not possible at this stage to understand it in animals.
Even sentience is a problem. I can make a good case that mammals are sentient. But what about fish? Or crustaceans? There are serious researchers who claim all of these animals can feel pain. These claims seem plausible, but I don't see the objective tests.
When I was a kid, my friend's mom brought home their little white curly dog after it had just gotten totally shaved for the summer. I sware, that dog was embarrassed. I had never seen it hide and whine under the couch like, ever. Eventually it would come out, and then we'd point and laugh at it (it really was incredibly funny looking), and then it'd run and hide and whine some more.
Maybe your friend's dog was embarassed; or maybe it was reacting to your behavior. For example, many dog owners believe their dogs display a guilty look after misbehaving. But a study shows that the so-called "guilty look" is a reaction to the behavior of the owner when the owner believes the dog has misbehaved.
Animals? Only humans have theories.
"Theory of mind" refers to the ability to recognize that individuals other than oneself have beliefs and desires. Humans have this ability. Some researchers claim that some other species have this ability, too. But the interpretation of this research is ambiguous, since the observed behaviors may have other explanations, such as prior trial-and-error learning.
These are all excellent questions which I shall answer the moment I figure out how to read the mind of a crow.
What about Gallup's mirror test? Don't you think that demonstrates self-awareness in chimpanzees, dolphins, and the other species that have passed the test?
I think that test only demonstrates witch animals have the capacety to realise that the animal they see is only a reflection i doubt it has much to do whit self-awareness and more whit their cognitive functions that descypher their optical imput.
It demonstrates that the animal knows it is seeing a refection of itself. In chimpanzees, for instance, the chimp will touch its own forehead when it sees a dab of paint on the forehead in the reflection.
When the fungus is ready to sporulate, the mycelia grow into the ant’s brain. The fungus then produces chemicals which act on the host’s brain and alter its perception of pheromones. This causes the ant to climb a plant and, upon reaching the top, to clamp its mandibles around a leaf or leaf stem, thus securing it firmly to what will be its final resting place.
Another question is how does genetic memory or instinct occur? Why am I instinctively afraid of spiders and snakes and heights? I see how being afraid of dangerous things is helpful but how do my genes remember that from previous encounters in other generations?
Visual images of snakes and spiders stimulate a brain network centered on the amygdala, which in turn triggers the fear response. Conscious processing (e.g., you realize its a rubber snake, not a real snake) can halt this porcess.
Some fears are learned. But our brains appear to be hardwired to recognize images of snakes and spiders.
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