Why are humans bilaterally symmetrical

A taxonomic clade, Bilateria, includes animals with bilateral symmetry. These animals also referred to as bilaterians have left and right sides to distinguish them from those with different form of symmetry e.

Bilateral symmetry in the plant kingdom is exemplified by the orchid and pea families. Synonym s :. Darwin's Finches are an example of natural selection in action. They are an excellent example of the way species' gene p..

Regulation of Biological Systems tutorials are focused on the modulation of biological systems from cell to population l.. This tutorial looks at the relationship between organisms.

It also explores how energy is passed on in the food chain an.. Does this penchant for order cloud our ability to see the universe accurately? A new book by theoretical astrophysicist Mario Livio explores the question. Birkhoff's formula relied on two abstract concepts: complexity and order or symmetry.

According to Birkhoff, if something is complex, it will be more appealing if it is less symmetrical. Alternatively, if something is highly-symmetrical, it is better if it is less complex. The formula seemed to make sense in theory, but there was one major problem: how to measure complexity and symmetry?

Birkhoff claimed there was a way to do this, but his methods were too subjective for most people's tastes and his formula was soon forgotten. Despite his failed effort, Birkhoff's idea that symmetry is a crucial determining factor for an object's aesthetic appeal is once again gaining credence in science, but in a slightly different form. In biology, recent studies have found that humans and other animals are highly attuned to symmetry in each other and often use it to gauge beauty and health during mate selection.

Sensitivity to symmetry, it seems, is ingrained into our behavior. Leonardo Da Vinci modeled his perfect human form after the proportions laid out by Vitruvius, an ancient Roman architect. Da Vinci's Best Ideas. Mario Livio, a senior astrophysicist at the Space Telescope Science Institute in Baltimore, wonders if our biological preference for symmetry is biasing our perception of the world, influencing what humans find beautiful or even affecting the way we conduct science.

The body plans of most animals, including humans, exhibit mirror symmetry, also called bilateral symmetry. They are symmetric about a plane running from head to tail or toe. Bilateral symmetry is so prevalent in the animal kingdom that many scientists think that it can't be a coincidence. After all, there are infinitely more ways to construct an asymmetrical body than a symmetrical one. And yet, fossilized evidence shows that bilateral symmetry had already taken hold in animals as early as million years ago.

For example, Standen says that symmetry is guiding even the fundamental process of cell division. An organism starts as a single cell and has to organize itself and its genetic material in a symmetrical way to ensure that each daughter cell has a copy of each gene before it splits.

Importantly, she notes, not all animals are bilaterally symmetrical. Some animals have radial symmetry with four or five axes, like starfish, jellyfish and sea urchins. The only creature on Earth who is not symmetrical in any way is the sponge. And why are E. Standen thinks it's likely because the symmetry that surrounds us in the real world guides human creativity and imagination.