Green Harvest, An Introduction to Biology

03/06/2026

Happy Birthday to
Lynn Margulis March 5, 1938 – November 22, 2011 was an American evolutionary theorist, science author, educator, and popularizer, and was the primary modern proponent for the significance of symbiosis in evolution.

Historian Jan Sapp has said that "Lynn Margulis's name is as synonymous with symbiosis as Charles Darwin's is with evolution."

In particular, Margulis transformed and fundamentally framed current understanding of the evolution of cells with nuclei – an event Ernst Mayr called "perhaps the most important and dramatic event in the history of life" – by proposing it to have been the result of symbiotic mergers of bacteria.

Margulis was also the co-developer of the Gaia hypothesis with the British chemist James Lovelock, proposing that the Earth functions as a single self-regulating system, and was the principal defender and promulgator of the five kingdom classification of Robert Whittaker.

Endosymbiosis theory

The chloroplasts of glaucophytes like this Glaucocystis have a peptidoglycan layer, evidence of their endosymbiotic origin from cyanobacteria.

In 1966, as a young faculty member at Boston University, Margulis wrote a theoretical paper titled "On the Origin of Mitosing Cells". The paper, however, was "rejected by about fifteen scientific journals," she recalled. It was finally accepted by Journal of Theoretical Biology and is considered today a landmark in modern endosymbiotic theory. Weathering constant criticism of her ideas for decades, Margulis was famous for her tenacity in pushing her theory forward, despite the opposition she faced at the time. The descent of mitochondria from bacteria and of chloroplasts from cyanobacteria was experimentally demonstrated in 1978 by Robert Schwartz and Margaret Dayhoff. This formed the first experimental evidence for her theory. The endosymbiosis theory of organogenesis became widely accepted in the 1980s, when the genetic material of mitochondria and chloroplasts was found to be different from that of the symbiont's nuclear DNA.

In 1995, English evolutionary biologist Richard Dawkins had this to say about Lynn Margulis and her work:
""I greatly admire Lynn Margulis's sheer courage and stamina in sticking by the endosymbiosis theory, and carrying it through from being an unorthodoxy to an orthodoxy. I'm referring to the theory that the eukaryotic cell is a symbiotic union of primitive prokaryotic cells. This is one of the great achievements of twentieth-century evolutionary biology, and I greatly admire her for it.""

https://en.wikipedia.org/wiki/Lynn_Margulis

02/28/2026

Look at this!
I can see why it was called the Valley of the Dreams!
That's for sure a paradise for geologists!

LEARN Geology

https://youtube.com/?si=4kGiBK5bIQ86Ess6

02/24/2026

Plants from a wonderful spot on Maui.

10/23/2025

10/23/2025

It is with great sadness that we announce the passing of 17 year-old Komodo dragon, MacLeod.

Over the last several weeks, staff noticed MacLeod's behavior change, including a refusal to eat. Through diagnostic imaging, a mass was discovered in his coelom. Given MacLeod's state, our staff elected for emergency surgery to remove it. While the removal of the mass was successful, MacLeod's health declined and he did not make it through the night.

The Phoenix Zoo was fortunate to be MacLeod's home since May of 2014. We deeply appreciate our amazing vet staff and ectotherm team, current and former, for the incredible care he was given through the years.

10/02/2025

Around 520 million years ago, evolution ignited. Oceans filled with strange new creatures, predators emerged, and biodiversity exploded in what scientists now call the Cambrian explosion. This turning point reshaped Earth forever—setting the stage for all complex life to come.

Explore the science behind the explosion of life: https://bit.ly/42I1EN9

📸 Sun et al. (2002) National Science Review / Wikipedia

09/18/2025

Meet the prehistoric giant that ruled the seas, a sea turtle so massive it could rival a small car

The fossil you’re looking at belongs to Archelon ischyros, the largest sea turtle ever known to science. First described in 1902, this incredible marine reptile lived about 70 to 80 million years ago during the Late Cretaceous period. Measuring over 4 metres (13 feet) from flipper to flipper and weighing nearly 2 tonnes, Archelon was the undisputed giant of the ancient oceans.

Unlike modern sea turtles, which have hard bony shells, Archelon had a leathery carapace reinforced with a framework of bones. This made its shell lighter and helped it glide effortlessly through the shallow seas of the Western Interior Seaway, which once split North America in two. Its powerful flippers were perfectly adapted for long-distance swimming, and its sharp, beak-like jaws were ideal for crushing molluscs, crustaceans, and perhaps even small fish.

Fossils of Archelon have mostly been found in South Dakota, a region that was completely underwater during its time. Imagine swimming in those warm inland seas with creatures like mosasaurs, ammonites, and giant fish sharing the waters, it was a true Cretaceous paradise teeming with life.

Strange yet interesting fact
The largest Archelon fossil ever found has a flipper span of more than 15 feet, wider than the height of a basketball hoop, making it one of the most impressive marine reptiles ever discovered.

09/17/2025

On National Hummingbird Day, we can marvel at one of the best-preserved hummingbird fossils ever discovered: Eurotrochilus, found in southeastern France and dating back 28 to 34 million years. This tiny bird already displayed many features seen in modern hummingbirds, including specialized wing and feather structures that allowed for agile flight and hovering.

Researchers estimate that hummingbirds diverged from their closest relatives, the swifts, around 42 million years ago. The most recent common ancestor of living hummingbirds appeared roughly 22.4 million years ago. This suggests that sometime between 40 and 20 million years ago, these birds migrated from Eurasia to the Americas, likely using the Bering land bridge as a route. Over millions of years, they diversified into the dazzling array of species we see today, each uniquely adapted to its ecological niche.

Fossils like Eurotrochilus give scientists a rare glimpse into the early evolution of hummingbirds, showing that many of the adaptations we associate with their modern lifestyle, like hovering flight and elongated bills, were already emerging in the Oligocene epoch. These discoveries also help clarify how small birds responded to climate changes and migrated across continents, laying the foundation for the incredible biodiversity we enjoy today.

Strange Fact: Despite their long history, hummingbirds’ tiny bones are so fragile that fossil evidence is extremely rare, making Eurotrochilus a remarkable and invaluable snapshot of their ancient lineage.