Guessing what aliens might look like has been entertaining kids, filmmakers, and scientists for years. If aliens exist, will they be like us or beyond our imagination? The answer to this question really depends on how we think about change at the deepest level.
Hollywood has given us its share of humanoid aliens over the years. At first, this is not necessary because, for special effects, someone needs to install tires. Ironically, now that CGI has made this possible, aliens sometimes appear as humans to help movie lovers connect with them—like James Cameron's Avatar.
We are the only way of life in the world that can be learned right now. They had the same origin about 3.5 billion years ago, but the number of this ancestor has increased to 20 million. The bodies of these animals are organized into 30 different bodies, which are divided into large groups called phyla.
Five-Eyed Fossil Opabinia may be a modern-day five eyed animal. Nobu Tamura/WikimediaBut when animals first diversified during the Cambrian "explosion" about 542 million years ago, body structure also varied. Consider the five eyed, trunked Obapinia pictured above, or the stalked, almost flower-like dinosaurs and our distant cousins, the chordate Pikachus.
Replaying the tape of life
in a famous experiment, biologist Stephen Jay Gould asked what would happen if we rewinded the "tape of life" and played it again. Gould argued for the importance of path in evolution: Change a small thing early, and the result will be greater over time. Throughout history as we know it, the Pika virus (image below) or something similar has survived and eventually killed off fish, amphibians, reptiles, mammals, and eventually ourselves.
What if it gets lost?
Did another group create geniuses who you can now read with five eyes instead of the usual two? If our origin on Earth is truly true, why do aliens evolving on different planets still look like us?
Pikaia - an early chordate, a group to which humans belong. Nobu Tamura/wikimedia
Evolutionary biologist Simon Conway Morris believes the answer lies in evolutionary convergence: the process by which distant animals become similar to each other. For example, the similar shapes of dolphins, tunas, and extinct ichthyosaurs all evolved independently in response to the same selection to move quickly and efficiently through water.
But what can we expect from exobiology? Carbon based biochemistry is good because carbon forms strong bones and durable materials but easily breaks bonds with other elements. Other elements, especially silicon and sulfur, form bonds that are less stable at Earth's temperature. Water or other solvents are also suitable. In order for evolution to occur, some mechanisms, such as DNA, RNA or some analogs, must be stored and replicated in their entirety. Although the first brain appeared early on Earth, it took approximately 3 billion years for different animal species to evolve.
So life on other worlds seems to have fallen to a single level.
On Earth, like Earth, radiation from the sun will be used in the biochemical process to produce energy. Efficient use of light for medium-sized multicellular primary producers will require a light harvesting system consisting of leaves and branches. Similar shapes and similar behaviors have evolved on Earth, so we can think of Earth's "plants" as having a wide range of knowledge like Earth.
But animals eat primary producers or each other, and there are many ways to do this. Finding food usually requires movement with the mouth first, which is why animals have a head and tail. Teeth, and sometimes jaws, evolved to accommodate and process food. The movement of the skin requires a special intersection structure (such as cilia, muscles, or legs) to have front and back. Often this also has bilateral (left/right) symmetry: in fact most animals in the "supergroup" are referred to as bilateral symmetry.
Why not smart big "line"?
But perhaps a creature with a large brain and intelligence could affect the difference between the stars? Insects are far from the most abundant species on Earth: Why don't aliens like them? Unfortunately, the external presence of bone makes growth difficult and requires a long time and regeneration. On Earth-like planets, all but relatively small land animals with other skeletons will collapse under their own weight during molting, and a certain size may be required for a suitably complex brain.
Giant weta: one of the largest weta insects. New Zealand Department of Conservation
The brain is very large in the world; in monkeys, whales, dolphins, dogs, parrots, crows, and octopuses, some tools and solutions may seem to intervene and have evolved many times. However, monkeys are very good at making tools. This is the part of walking on legs that allows at least the forelimbs, and because of the dexterity of our fingers (which is also important for the basis of written words).
Ultimately, the jury is still out on what, if anything, alien intelligence means for us.
It may or may not be important that humans only have two eyes and ears (just enough for vision and hearing). ) and only two legs (placed from the first four legs, which are more stable). Many other bodies also arise in pairs as a result of mutual cooperation and may not be mutually exclusive in our evolution. But other details of our body plan may be nothing more than coincidence. The fact that our hands and feet have five fingers is a result of our first four-legged ancestors' obsession with five fingers. Relatives made seven to eight attempts.
In fact, most animals accidentally become "locked" during development, leaving a stereotyped body plan and inflexibility over evolutionary time. Seasonal change is one of the biggest problems in evolutionary biology and will help us better understand how alien life differs from our own.
Currently the main way we look for intelligent life in space is by listening to radio waves or gamma rays. These efforts have focused on stars with Earth-like planets because they are thought to be potentially habitable. After all, it is easier to find "the life we know" than the life we don't know. Matthew Wills is Professor of Evolutionary Paleontology at the Milner Center for Evolution at the University of Bath.
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