Systematic Classification of Life by Aron Ra

Unfortunately, it seems that the project he is talking about in the video is either defunct or currently closed, though I have seen it in the past and other similar websites currently exist.

When Darwin wrote his book, no transitional fossils had been found. However, before his death, some were already discovered. We have now found hundreds of transitional species, even when you're using the strictest definition.

Linnaeus was the first to attempt a systematic classification of life into types. He used his huge understanding of botony and comparative anatomy, he ran into a lot of issues, and realized that there was a kind of tree-like structure, but couldn't understand why.

Monophyletic

Descending from one common ancestor.

Phylogenetic

Related via heritable traits which can be seen in DNA or morphology (structures like hand bones, etc.)

Taxonomy

Categorizing things, especially living things, into different groups.

The further back in time you look, the simpler and more similar all living things are, until you end up back at single cells.

I once read that the reason that evolution is so hard to see and understand in our modern world is because broad extinction events have pruned a lot of intermediate animal types.

The first 80% of life on Earth was single-celled.

1. Cellular
2. Metabolism (they break down nutreints
3. Growth
4. Reproduction
5. Evolution and Adaptation
6. Respond to Stimuli
7. Homeostasis (they maintain a balanced internal environment, and if they don't they die)

Viruses are not considered "alive" because they don't need to maintain an internal environment.

It's a common misconception that life arouse from "inorganic matter", however this is a miscommunication. We often say "inorganic matter" to mean something which is sterile and devoid of life. However, this has a specific technical meaning in science, which can lead to incorrect assumptions. Life, generally speaking, is made out of what science calls "organic chemicals" like carbon, hydrogen, oxygen, and nitrogen.

It's not accurate to say that we evolved from microbes, because they can share genetic information just by touching each other. Evolution requires descent with modification, and the way microbes share DNA means that evolution, in the strict sense, doesn't really apply to them. So, evolution proper really only operates on multicellular eukaryotes.

Our planet was probably hit by another planet around the size of Mars, and the debris created by this is what created the moon.

Meteorites can contain dozens and dozens of amino acids and complex molecules. RNA can even create itself spontaneously given the right ingredients and environment!

The early climate is completely different from today: it was much hotter and much more radioactive. Early bacteria are anerobic, meaning that they don't need oxygen to survive. Blue-green algae is one such organism, that uses sunlight to create food, and produces oxygen as a waste product. Plants do photosynthesis because they have blue-green algae living inside of their cells, called "chloroplasts".

All animals are Eukaryotes. Eukaryotes are large cells, much larger than prokaryotes. They have DNA inside of a nucleus, and have organelles. Some might have developed internally, but others are known to be captured microorginisms, such as chloroplasts and mitochondria. In fact, scientists recently caught a new organelle being captured!

This series is all about cladistics. A clade contains all of a group as well as all of it's descendents, similar to Russian nesting dolls. Linnean taxonomy is paraphyletic, meaning that it names a group, but a group doesn't include its descendants. So in Paraphyletic taxonomy dinosaurs and birds are distinct groups, but in monophyletic/phylogenetic classification, birds are a specialized type of dinosaur.

The furthest back cladistic evolution can go is the three way split between the bacteria, archaea, and eukarya -- or sliced a different way, between prokarya and eukarya. All known life on our planet falls into one of these groups.

Things changed very slowly in the beginning, then sped up rapidly.

Vast algae blooms filled the oceans (but not yet the sky) with oxygen, and nothing lived on the land.

Metazoa is better known as "animalia"

Animals are uniconts, meaning cells having one flagellum. It includes opisthokonts (who push with their flagella) such as animals. Most modern opisthokonts only have flagella on their reproductive cells like sperm.

Animalia (Metazoa)must be multi-cellular.

Modern cladistics includes many more clade than you might assume, when you consider the historical alternitive of only 7 under Linean taxonomy.

Parazoa are animals without layers of clearly defined tissues. In contrast Eumetazoa have skin cells. Parazoa don't have internal digestive systems.

One of the laws of evolution is that the children of two closely related species are more similar than their adult forms.

Simple animals didn't have internal digestion yet. First they formed a "pouch" gut. When this went all the way through, bilateria (animals with bilateral symmetry) were the result.

Sexual reproduction allows for faster evolution, and so to predator-prey relationships.

One of the earliest and most pronounced trends of bilateral animals is "cephelization" or the clustering of neurons and sensory organis into a "head".

Triploblasts = 3 layer animals. Endoderm = skin cells. Ectoderm = nervous system. Mesoderm = connective tissue and muscles.

Nephrazoa have a through gut with mouth and anus, they have a tissue lined body cavity. and they have a fluid in that cavity.

Protostomes, the mouth opens first. The Deuterostomes, the mor common group including humans, the anus opens first.

In general, protostomes have blue blood (hemocyanin) and deurerostomes have hemoglobin (red blood)

Chordata has a spinal cord, though they don't necessarily have vertebra.

Olfactorus -- we gained nostrils. Craniata - a network of cartelidge or bone to create a "skull". Vertebrata -- having spine

gnathostomata = fish with jaws. they were now able to bite

Bony fish developed swim bladders, and over time were able to use them as proto-lungs, taking "sips" of air in stagnant waters.