Evolution happens like a movie, with frames moving by both quickly and gradually, and we often can’t see the change while it’s occurring. Every time we find a fossil, it’s a snapshot back in time, often with thousands of frames missing in between, and we’re forced to reconstruct the whole film. Life is what happens in between the snapshots.
This is what almost four billion years of human evolution looks like when it’s condensed down to ten seconds, thanks to the fine folks behind the original Cosmos.
From self-replicating bags of chemistry to bacteria to crude multicellular blobs to tiny swimming monsters to creeping fish to fuzzy proto-mammals to weird, naked, two-legged apes … every cosmic blink holds a beautiful story.
If you’d like to retrace your steps along the path of time that ends with you, I recommend this awesome Wikipedia page.
Some claim that Evolution is just a theory, as if it were merely an opinion.
Nature never appeals to intelligence until habit and instinct are useless. There is no intelligence where there is no need of change.
Sometimes evolution is stupid, and the human body is proof. Here are the most problematic physical and behavioral “scars of evolution” we humans have to deal with.
In some respects, these “scars” can be seen as vestigial traits, but that’s not quite accurate. Rather, they’re examples of the various trade-offs and side-effects of evolution. They’re also not physical or psychological limitations per se (like our poor sense of smell or inability to grasp large numbers — those traits weren’t adaptive in our recent evolutionary past).
The Dual Function of the Pharynx
This is one of the most problematic “features” of the human body — and the cause of innumerable deaths throughout human history. Like many other primates, we’re forced to use the same anatomical structure for both ingestion and respiration. But when obstructed, airflow is blocked, which can lead to choking, and in some cases, death.
Our Inability to Biosynthesize Vitamin C
Vitamin C plays a crucial role as an anti-oxidant and in collagen synthesis. But certain animals, such as primates, guinea pigs, and some bats and birds, have completely lost the ability to synthesize this compound. So, when Vitamin C-rich food sources are scarce, such as fruits, we experience a weakened immune response.
Also, because we can’t make all the vitamins we need, we carry a host of deadly bacteria in our bowels, which produce them for us. But when this process is disrupted, like a hole in the intestine, it can flare into peritonitis.
The Close Proximity of our Genitals to our Rectum
Not only is this aesthetically displeasing, it’s also unhygienic. Combined with our short urethras — especially in women — this leads to frequent urinary tract and bladder infections (UTIs) (remember, front to back, ladies).
Our Multi-Function Genitals
Relatedly, our genitals are forced to perform multiple functions. While on the one hand it can be seen as conservation in design, it creates health problems. Again, it’s unhygienic. For women, sexual intercourse pushes bacteria further into the urethra, leading to UTIs. Additionally, both men and women can contract UTIs from two sexually transmitted bacteria, chlamydia and mycoplasma. And of course, for women, this is also the part of the body where, in addition to sex and urination, newborn babies come out.
The Extremely Narrow Human Birth Canal
Speaking of which, human females have an unreasonably narrow birth canal, resulting in significantly increased risks to both mother and child during birth. In fact, death in childbirth used to be the leading cause of death for women during their reproductive years. This is a consequence of our quick evolutionary leap from quadrupeds to bipeds, resulting in our narrow pelvis — the passage through which newborn babies pass.
Our Over-Loaded Lower Backs
This is also a consequence of our transition from four-legged to two-legged creatures. According to paleoanthropologist Bruce Latimer of Case Western Reserve University in Cleveland, Ohio,
When humans stood upright, they took a spine that had evolved to be stiff for climbing and moving in trees and rotated it 90 degrees, so it was vertical. But so as not to obstruct the birth canal and to get the torso balanced above our feet, the spine has to curve inwards, creating the hollow of our backs. That’s why our spines are shaped like an “S.” All that curving, with the weight of the head and stuff we carry stacked on top, creates pressure that causes back problems. “If you take care of it, your spine will get you through to about 40 or 50” said Latimer. “After that, you’re on your own.”
The Overly Complicated Human Foot
Anthropologist Jeremy DeSilva of Boston University put it this way:
Starting with the foot, DeSilva held up a cast with 26 bones and said: “You wouldn’t design it out of 26 moving parts.” Our feet have so many bones because our ape-like ancestors needed flexible feet to grasp branches. But as they moved out of the trees and began walking upright on the ground the foot had to become more stable, and the big toe, which was no longer opposable, aligned itself with the other toes and our ancestors developed an arch to work as a shock absorber. “The foot was modified to remain rigid” said DeSilva. But the bottom line was that our foot still has a lot of room to twist inwards and outwards, and our arches collapse. This results in: ankle sprains, plantar fasciitis, Achilles tendonitis, shin splints, and broken ankles. These are not modern problems; fossils show broken ankles that have healed as far back as 3 million years ago.
A better design for upright walking and running, DeSilva said, would be a foot and ankle like an ostrich. An ostrich’s ankle and lower leg bones are fused into a single structure, and their foot has only two toes that aid in running. “Why can’t I have a foot like that?” asked DeSilva. One reason is that ostriches trace their upright locomotion back 230 million years to the age of dinosaurs, while our ancestors walked upright just 5 million years ago.
The “Blind Spot” in Our Eyes
Our so-called “blind spot” is the result of a quirk that happens during embryological development. To deal with this, we’ve had to evolve elaborate and costly perception-correcting mechanisms. Esther Inglis-Arkell describes it like this:
Light gets into the eye by passing through the pupil. It hits the retina at the back of the eye. The retina is covered with light-sensing proteins. They relay what they sense to the optic nerve which carries the information back into the brain. The problem is, the optic nerve ends in the field of the retina itself. It creates a dark spot. Most of the time, the other eye will see what’s happening in its partner’s blind, but if the blind spots overlap while looking at a certain object, or if the person is only looking through one eye, the brain just fills in the spot looking at the surrounding picture.
A Single Set of Adult Teeth
This is where evolution got unreasonably cheap on us, providing humans with just one set of teeth for our entire adult lives. Once we hit 35, our teeth start to go — one of many signs that evolution primed us for reproduction, followed by a brief period of child-rearing, and pretty much nothing else.
Our fondness for sweet, salty, and fatty foods
Our bodies need sugar, salt, and fat — just not in extreme quantities. But in a state of nature, these foods are often scarce or difficult to preserve. That’s why we find these food unreasonably delicious and irresistible. But most of us now live in a world of tremendous abundance, and we consume these foods in ridiculous quantities, leading to all sorts of modern health problems.
Humans have a kind of ingrained fear or distrust of the “out-group”. It’s a previously adaptive trait that binds small groups of individuals together and prevents them from wandering off or joining other groups. But it also leads to ethnocentrism and divisions between groups. Studies show that oxytocin, while strengthening feelings of trust between individuals, increases fear of “the other”. This characteristic was obviously important back when we lived in family clans or tribal arrangements, but today it leads to all sorts of social problems, including racism, prejudice, and our inability to empathize with people we don’t immediately know.
Any Number of Cognitive Biases
Many of our cognitive biases — annoying glitches in our thinking that cause us to make questionable decisions and reach erroneous conclusions — are a consequence of our limited intelligence and predisposed tendencies. Examples include the confirmation bias (we love to agree with people who agree with us), our tendency to neglect or misjudge probability, and the status-quo bias (we often make choices that guarantee that things remain the same). Some of these are adaptive traits, but others are simply cognitive deficiencies.
Attention Deficit Hyperactivity Disorder
This is an example of how we’ve potentially pathologized a perfectly “normal” human psychological characteristic. Because ADHD appears to have a genetic component (it affects about 5% of school-aged children), questions have been raised about its prior role as a trait required for survival, namely its adaptive function in hunter, fighter, and wader theories. But today, we see it as something maladaptive — something that needs to be treated. Put another way, and like our penchant for sweet, salty, and fatty foods, it’s a trait that’s not so much nonoptimal as it’s ill suited for present-day society.
Bill Nye Debates Ken Ham
In case you missed it, the debate in full. All the videos I’ve found don’t start until 13 mins in. Skip ahead ;)
Top 5 misconceptions about evolution: A guide to demystify the foundation of modern biology.
Here is an infographic to help inform citizens. From my experience most people who misunderstand evolution are actually misinformed about what science is and how it operates. That said, here are five of the biggest barriers faced when one explains evolution - I have faced these and they are documented in the literature.
I hope you can build on my work and improve the communication between the scientists and the public.
Want to do more? If you want to donate to the cause of science education I suggest the National Center for Science Education http://ncse.com, your local university, or an equivalent organization. Volunteering at schools and inviting scientists into classrooms are two ways to encourage an informed society. Attend hearings if school boards start questioning evolution’s role in public curriculum. Raise a storm if anyone tries to ban science. Plus, it never hurts to reblog a well made evolution post.
Thank you followers for all your support!
'Be different or die' does not drive evolution
A new study has found that species living together are not forced to evolve differently to avoid competing with each other, challenging a theory that has held since Darwin’s Origin of Species.
By focusing on ovenbirds, one of the most diverse bird families in the world, the Oxford University-led team conducted the most in-depth analysis yet of the processes causing species differences to evolve.
They found that although bird species occurring together were consistently more different than species living apart, this was simply an artefact of species being old by the time they meet. In fact, once variation in the age of species was accounted for, coexisting species were actually more similar than species evolving separately, opposite to Darwin’s view which remains widely-held today.
'It's not so much a case of Darwin being wrong, as there is no shortage of evidence for competition driving divergent evolution in some very young lineages,' said Dr Joe Tobias of Oxford University's Department of Zoology, who led the study. 'But we found no evidence that this process explains differences across a much larger sample of species.
In the six million years since the human and chimpanzee lines first diverged, chimpanzees have evolved, but, in comparative terms, their behaviour and lifestyles have barely changed. Human behaviour and lifestyles have clearly transformed out of all recognition. Humans have learnt to learn from previous generations, to improve upon their work, and to establish a momentum to human life and culture that has taken us from cave art to quantum physics and the conquest of space. It is this capacity for constant innovation that distinguishes humans from all other animals. All animals have an evolutionary past. Only humans make history. And in that context, and that context alone, can we understand what is distinctive about human culture.
Baffling 400,000-Year-Old Clue to Human Origins
Scientists have found the oldest DNA evidence yet of humans’ biological history. But instead of neatly clarifying human evolution, the finding is adding new mysteries. In a paper in the journal Nature, scientists reported Wednesday that they had retrieved ancient human DNA from a fossil dating back about 400,000 years, shattering the previous record of 100,000 years. The fossil, a thigh bone found in Spain, had previously seemed to many experts to belong to a forerunner of Neanderthals. But its DNA tells a very different story. It most closely resembles DNA from an enigmatic lineage of humans known as Denisovans. Until now, Denisovans were known only from DNA retrieved from 80,000-year-old remains in Siberia, 4,000 miles east of where the new DNA was found. The mismatch between the anatomical and genetic evidence surprised the scientists, who are now rethinking human evolution over the past few hundred thousand years. It is possible, for example, that there are many extinct human populations that scientists have yet to discover. They might have interbred, swapping DNA. Scientists hope that further studies of extremely ancient human DNA will clarify the mystery. “Right now, we’ve basically generated a big question mark,” said Matthias Meyer, a geneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and a co-author of the new study. (via Baffling 400,000-Year-Old Clue to Human Origins - NYTimes.com)
The Evolution of Life
In its 4540 million (4.54 billion) years circling the sun, Earth has provided a home for life that has become more and more complex. [The timeline can be seen here in more detail.]
- for the last 3600 million years, simple cells (prokaryotes);
- for the last 3400 million years, photosynthetic cyanobacteria
- for the last 2000 million years, complex cells (eukaryotes);
- for the last 1000 million years, multicellular life;
- for the last 600 million years, simple animals;
- for the last 550 million years, bilaterians,
animals with a front end and a back end,
as well as an upside and a downside;
- for the last 500 million years, fish and proto-amphibians;
- for the last 475 million years, land plants;
- for the last 400 million years, insects and plants with seeds;
- for the last 360 million years, amphibians;
- for the last 300 million years, reptiles;
- for the last 200 million years, mammals;
- for the last 150 million years, birds;
- for the last 130 million years, flowers;
- for the last 60 million years, the primates,
- for the last 20 million years, the family Hominidae (great apes);
- for the last 2.5 million years, the genus Homo (human predecessors);
- for the last 200,000 years, anatomically modern humans.
Image retrieved here [source unknown]
How did feathers evolve? A TED-Ed animation explores.
When you think about it, feathers are pretty amazing. The most complex integumentary structures (y’know — integumentary — stuff like skin, hair, scales, hooves) found in vertebrates, feathers have graced the bodies of animals since the age of dinosaurs, evolving to assist in taking flight, wicking off water, and looking fly for the ladies.
Well-Preserved Find 1.8 Million Years Old Drastically Simplifies Evolutionary Picture
- by Robert Lee Hotz
"A newly discovered 1.8 million-year-old skull offers evidence that humanity’s early ancestors emerged from Africa as a single adventurous species, not several species as believed, drastically simplifying human evolution, an international research team said Thursday.
The skull—the most complete of its kind ever discovered—is “a really extraordinary find,” said paleoanthropologist Marcia Ponce de Leon at the University of Zurich’s Anthropological Institute and Museum, who helped analyze it. “It is in a perfectly preserved state.”
Unearthed at Dmanisi in Georgia—an ancient route in the Caucasus for the first human migrations out of Africa—the skull was found at a spot where partial fossils of four other similar individuals and a scattering of crude stone tools had been found several years ago. They all date from a time when the area was a humid forest where saber-tooth tigers and giant cheetahs prowled. Preserved in siltstone beneath the hilltop ruins of a medieval fortress, the remains are the earliest known human fossils outside Africa, experts said.
David Lordkipanidze, director of the Georgian National Museum, who led the team, reported the discovery in Science. The primitive skull was first uncovered on Aug. 5, 2005—his birthday. “It was a very nice present,” he said.
Taken together, the finds at Dmanisi are especially important because experts in evolution could analyze the physical differences between individuals living in the same place at the same time almost 2 million years ago, when humankind first emerged from Africa to people the world, according to Yale University anthropologist Andrew Hill.
"It gives you a chance to look at variation for the first time," said Dr. Hill, who was not involved in the discovery" (read more).
***Hmm. I need to read the study ASAP.
(Source: Wall Street Journal)
Those who cavalierly reject the Theory of Evolution, as not adequately supported by facts, seem quite to forget that their own theory is supported by no facts at all. Like the majority of men who are born to a given belief, they demand the most rigorous proof of any adverse belief, but assume that their own needs none.
"In the age of information, ignorance is a choice." - Donnie Miller
There is overwhelming evidence for the theory of evolution, Those who wish to find this evidence need only an open mind and the desire to learn, as the evidence is not at all kept in hiding. Below are a few credible sources for those who are curious about what evolution is and the supporting evidence for the theory. Please add to this list as you see fit.