On Earth, intelligent life has evolved only on land, as far as we know. To be clear about the topic, we need to define what criteria we will use for intelligence. Intelligence is a murky concept. For hominids, it is connected with using tools and being able to communicate, but drawing a clear line is a slippery thing. One way to approach the task is to make the cut above what any animal other than humans can do in the present era. Chimpanzees can assemble parts to make long poles, for instance, that are then used to reach things on the other side of barred openings. If this is not going to be intelligent, then we need to make fashioning things, for example, chipping rocks, as the minimum level.
For communication, there is a wide variety of communication in the animal world, including all manner of warning signals from birds, path information in bees, learning by example in beavers and many other animals, and so on. Perhaps a threshold for intelligence could be set at the level of a rudimentary grammar, such as noun verb combinations. Since we do not understand and cannot interpret the communications of the larger sea mammals, this might be too low.
In order to fashion components of tools, the undersea creature would have to be able to make changes in something, such as a rock or a piece of a plant. It would need a way to hold the object. Earth’s sea does not have trees or other climbable plants that larger animals could use to escape from predators or hunt for fruits or other edibles. Perhaps the lack of underwater surrogates for trees is the deciding factor on why intelligence did not develop first underwater here on Earth. There is no use for climbing when any mobile creature can swim to the top or bottom of the plant. Furthermore, developing appendages for grasping rocks would put the creature at a disadvantage for swimming fast and maneuvering sharply. Thus, at first glance, underwater intelligence is likely barred by the ease of three-dimensional travel in the water. On the land, considering non-flying animals, travel is two-dimensional following the terrain, except for climbing trees. The ability to go vertically up plants may provide an advantage, and evolving grasping appendages to do this would be encouraged. Then these could be used to grasp other objects, and intelligence for the first criteria could move forward.
Before leaving this area, consider if it would be possible for any grasping appendages to develop in the ocean. There are plenty of creatures in Earth’s oceans which are restricted to the sea bed. One other obstacle seems apparent, however, the viscosity of the water. If something like a lobster developed the ability to more flexibly grasp a stone, there is not much that can be done with it. In air, a stone can be moved rapidly, either to smash something on the ground, or to hit something at a distance. In the water, the stone would not achieve the same speed, and the effects would be much less. Probably the effect would be so much less that it would not be favored, as it has not been. So, three dimensional motion and viscosity seem to close the book on tool usage underwater.
Mammals living in the sea are thought to be descended from land mammals which evolved back to sea-living creatures. This means that the communication skills they might possess would not necessarily have originated in the oceans. In other words, a creature that evolved in a pathway wholly restricted to ocean life may not have the ability to create the complex sounds that whales and dolphins do. It may well be that the predecessor animals had some sound communication abilities, and these were preserved, although adapted, when the reverse migration took place. Non-mammalian sea creatures on Earth do emit some noises for defensive signals or for finding mates, but there is no complex communication.
Let’s imagine there was a planet with no moon, and the tides from the sun were small. Perhaps the planet had a very long day. In an ocean on a planet like this, there is not the constant beating of water in shallow areas that we have on earth. With neither winds nor tides to drive flows, water might be calm in the shallows, and more sturdy plants could develop, with trunks of higher strength than Earth’s seaweeds. If the trunks were strong enough, some bottom-dwelling sea creatures might be able to fashion something out of them. If not tools, perhaps dwellings for protection against predators, or corrals for farming some type of mobile sea life. Tools for dealing with plant life, in a kind of underwater farming, might also be of positive benefit when evolution came calling.
The moon is believed to have served to lengthen the day, so the combination of a lack of a moon and a very long day might be not self-consistent, unless there was a way for a planet to either be formed with little spin, or to otherwise lose it. Venus has no moon and a very low rotation rate, and one explanation for the difference in rotation rate is that Venus was impacted in such a way that when it condensed, it had a low spin. Alternately, solar tidal attraction on the crust slowed down the spin. So, no moon and low spin are compatible.
This means that if Venus and Earth had switched places, with the moon being on the second planet, not the third, and spins were low on the new third planet, there could have possibly, conceivably, developed there some intelligent life in the shallow waters of the oceans. Social organization would be necessary to spur the development of communication, as creatures that live independently have so little use for it that it would be superfluous, except for the uses that our fish and other non-mammalian sea life have. There does not seem to be any barrier to some Venus-prime sea life developing a social grouping, provided it did not give any advantage to the predators living there.
In such a novel environment, there are almost no bounds on imagining creatures that might evolve in it. We have only Earth creatures to use as examples, such as octopi or crustaceans. Modifying their appendages to provide some ability to cut and manipulate plant parts does not seem absurd, and neither does having the ability to produce sounds, either from a special organ able to vibrate in liquid or from other appendages used for friction. So, once we pass by the equivalent Great Filter of Trees, but an underwater version, there does not seem to be any immediately obvious reason to assume intelligent creatures could not evolve on a planet far different than Earth. The planet does not even need a land surface, just shallow areas where there are enough photons to evolve chlorophyll and provide a sufficient energy source.
No comments:
Post a Comment