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Many of us are returning to work or school after spending time with relatives. summer period. Sometimes I wonder how I relate to these people who seemingly have nothing in common (especially with particularly annoying relatives).
But evolutionarily speaking, if we go back far enough in time, we all share a common ancestor. This means that many functions of our bodies go back thousands or even millions of years in the great genealogy of life.
In biology, the term “homology” relates to structural similarity based on descendants from a shared common ancestor.
Consider the similarity between a human hand and a bat’s wing. whale flipper. All of these have specialized functions, but the underlying body plan of the bones remains the same.
This differs from “similar” structures such as insect and bird wings. Although dragonfly wings and parrot wings perform similar functions, they arise independently and do not share the same evolutionary origin.
Here are five examples of ancient traits that are still found in humans today.
one step ahead
What makes us human? This question has puzzled scientists and scholars for centuries. Today it seems relatively easy to tell who is human and who is not. fossil On record, things quickly become unclear.
Do humans begin with the origins of our own species, Homo sapiens, 300,000 years ago? Or does it go back to a split with other great apes? Whatever line you draw to identify the origin of the human race, one thing is certain. Habitually his act of walking around on two legs, known as “bipedalism”, is one of the great strides of our ancestors.
These big brains of ours have spurred an explosion of important concepts in thinking about art, culture, language, and what makes us human (Source: Getty Images/Thinkstock).
Almost every part of the skeleton walking Stand upright on all fours. These indications include the alignment and size of the leg bones, hip bones, knees, legs, and spine.
Importantly, fossil skulls show a rapid increase in brain size immediately after starting to walk upright. This required the pelvis to be modified to allow babies with large brains to pass through the wide birth canal.
our expansion pelvis The iliac flare (sometimes called the iliac flare) is a homologous feature shared by several lineages of early fossil humans, and all humans alive today.
These big brains of ours have spurred an explosion of art, culture and language, concepts important in thinking about what makes us human.
hole in your head
in addition to you eyeball Sitting in your eye socket, you might be surprised to learn that there are other large holes (known as windows) in your skull.
A single window on each side of the human skull connects us to a common ancestor more than 300 million years ago.
Animals with this single window in their skull are known as synapsids. The word means “fused arches” and refers to the bony arches beneath the openings in the skull behind each eye.
Today, all mammals, including humans, are synapsids (but reptiles and birds are not).
Other famous prehistoric synapsids include the often misidentified Dimetrodon. Ancient sail-supported reptiles are often mistaken for dinosaurs. However, due to its vast limbs and single temporal fenestrae, it instead belongs to a lineage sometimes referred to as “mammal-like reptiles”, although the more accurate term synapsid is preferred.
10 little fingers and 10 little fingers
I’m typing this article on my computer using 10 fingers (fingers and thumbs; fingers also point toes, but my fingers don’t reach the keyboard).
A pattern of five fingers on a human hand or foot, known as a “pentagram”, is found in most amphibians, reptiles and reptiles. bird and mammals.
But fish don’t have fingers and toes, so when did fingers first evolve? is described. We used powerful imaging techniques to peer inside a 380-million-year-old fossil called Elpistostege in Quebec, Canada, revealing the oldest fish fingers! In particular, the first fish to evolve fingers still retained fin rays around the fingers, so these bones would not have been visible to the outside of the animal.
The earliest tetrapods (four-legged animals with backbones that eventually migrated from water to land) “experimented” with digit numbers and are sometimes found with 6, 7 or 8 digits. was.
These earliest tetrapods probably still lived in water. This arrangement most likely emerged as a practical solution to weight loading on land.
long teeth
is your mind wandering brush teethSo, have you ever wondered how evolutionarily old your pearly whites are? described the teeth. This startling discovery pushes the minimum tooth age back by another 14 million years from previous findings.
This means that our dentition dates back 439 million years.
Chinese jawed fish teeth have many features found in other modern jawed vertebrates (Source: Getty Images/Thinkstock)
A very early jawed vertebrate, the new fish was named Qianodus duplicis and is known only from isolated, specialized teeth known as ‘whorls’. Spiral teeth are strange rows of teeth that curl on themselves in a spiral pattern (most famously present in the sawshark, helicoprion).
Nonetheless, the teeth of Chinese jawed fish have many features found in other living jawed vertebrates, and may have relevance in understanding the evolution of our own bruxism. I’m emphasizing. Chop it!
grow the spine
“Stand up” means to be brave and confident. The first animals to do so must have had the courage to venture into the perilous ancient seas 500 million years ago.
First, these worm-like animals evolved a “notochord.” This is a stick made of cartilage that runs along the back of the body. This allowed the attachment of segmented muscle blocks and a long tail extending beyond the anus.
All animals with a notochord are called chordates, and include over 65,000 species, from sea squirts to seagulls.
To get an idea of the first chordates, today we can look to animals such as the lancelet (also known as the lancelet or branchiostoma). Amphioxus look a bit like small primitive fish without fins. It swims by undulating its body left and right.
Next are those with well-arranged heads (tegmentous animals) and those in which the notochord is replaced by a backbone in adulthood (vertebrates).
The spine is made up of individual segmented bones (vertebrae) that fit together in specific interlocking patterns. There are some intriguing fossils representing the earliest known examples of vertebrates, such as Metaspriggina, known from Canada, and Haikouichthys, from China, in rocks over 500 million years old.
Thus, we humans share many ancient features of our bodies, such as a large brain and wide pelvis with upright walking, a skull with a single opening, bony arches, fingers, toes, teeth, and spinal cord.
So it might be worth remembering that, in the words of poet and activist Maya Angelou, we are more alike than dissimilar.
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