Even if there are a number of planets that could support tectonics, running water and the chemical cycles that are essential for life as we know it, it seems unlikely that any of them would look like Earth.

The reason? Plants.

A series of articles in the journal report that both vascular and non-vascular plants (mosses, liverworts, algae) shaped the surface of Earth, affecting the oceans and climate of our planet as they began to appear 470 million years ago.

Vascular plants defined the way water flowed on the Earth. One article describes the interplay of plant evolution and river formation. Scientific American offers a summation:

Before the era of plants, water ran over Earth’s landmasses in broad sheets, with no defined courses. Only when enough vegetation grew to break down rock into minerals and mud, and then hold that mud in place, did river banks form and begin to channel the water. The channeling led to periodic flooding that deposited sediment over broad areas, building up rich soil. The soil allowed trees to take root. Their woody debris fell into the rivers, creating logjams that rapidly created new channels and caused even more flooding, setting up a feedback loop that eventually supported forests and fertile plains.

Another article in Nature Geoscience examines how early non-vascular plants affected the planet dramatically—causing global cooling and mass extinction in the oceans. British researchers working in the lab and with computer simulations discovered that these first plants caused the weathering of calcium and magnesium ions from silicate rocks, such as granite, in a process that removed carbon dioxide from the atmosphere, forming new carbonate rocks in the ocean. This cooled global temperatures by around five degrees Celsius.

In addition, by weathering the nutrients from rocks, the first plants increased the quantities of both these nutrients going into the oceans, fuelling productivity there and causing organic carbon burial. This removed yet more carbon from the atmosphere, further cooling the climate by another two to three degrees Celsius. It could also have had a devastating impact on marine life, leading to a mass extinction that has puzzled scientists.

The effect of plants on our planet is profound, remarks Liam Dolan of Oxford University, a researcher on the non-vascular plant study.

For me the most important take-home message is that the invasion of the land by plants—a pivotal time in the history of the planet—brought about huge climate changes. Our discovery emphasizes that plants have a central regulatory role in the control of climate: they did yesterday, they do today and they certainly will in the future.

Image: Dog Walking Girl/Wikipedia

Or so goes a new study in published in Biology Letters last week. According to that abstract:

We conclude that the mechanism [genital break-off] may have evolved in response to sexual cannibalism and female-controlled short copulation duration.

Dang! You have to respect evolution!

And that’s the theme of a new exhibit opening at the Academy later this week: Animal Attraction—“sex drives evolution; nothing in life is more important.” The exhibit includes animals, specimens, images, videos and the weird and wild stories behind animal reproduction. In one species, the coral banded shrimp, the deviant mating behavior is monogamy. Well, sociopathic monogamy. We’ve produced a Science in Action video to supplement the exhibit explaining the mating habits of nearby elephant seals and banana slugs—very different mating strategies, but equally dangerous.

Which brings us back to these Nephilengys malabarensis spiders. As Ed Yong reports in Nature News:

Male spiders deliver their sperm through a pair of structures known as palps, which are found on the sides of their heads. By observing sexual encounters between 25 pairs of virgin N. malabarensis, [lead author Daiqin] Li’s group found that every coupling ended with damage to the male’s palp. In 12% of cases it was partially severed; in the rest it snapped off completely.

Yikes! But not only does the palp continue to deliver sperm to the female spider, it also blocks the entrance should she encounter another male spider. And, as we reported a couple of weeks ago, even as a eunuch, the male spider is still tough, actually becoming better fighters “without their heavy palps,” says Yong.

Passing along their genes long after mating, becoming better fighters and, perhaps most importantly, staying alive—these spiders are highly evolved to survive. Well done!

Image: Joelyn Oh

The proposal to reduce emissions came from an international team publishing in Science. Led by Drew Shindell of NASA Goddard, the team looked to other causes of global warming, excluding the carbon dioxide and fossil fuels that always cause a great debate. In their new study, they propose 14 key air pollution control measures that, if implemented, could slow the pace of global warming, improve health and boost agricultural production.

Their methods limit black carbon and methane, which would have a more immediate impact because these two pollutants circulate out of the atmosphere more quickly. The New York Times offers some of the solutions:

…encouraging a switch to cleaner diesel engines and cookstoves, building more efficient kilns and coke ovens, capturing methane at landfills and oil wells, and reducing methane emissions from rice paddies by draining them more often.

It’s a win-win proposal. “Protecting public health and food supplies may take precedence over avoiding climate change in most countries, but knowing that these measures also mitigate climate change may help motivate policies to put them into practice,” Shindell says.

Less than a week later, the locally based non-profit National Center for Science Education (NCSE) announced that it would support teachers who experience resistance to climate change education in their classrooms. Several years ago, they announced similar support for evolution education.

And the LA Times reports that sadly, the support is necessary:

Texas and Louisiana have introduced education standards that require educators to teach climate change denial as a valid scientific position. South Dakota and Utah passed resolutions denying climate change. Tennessee and Oklahoma also have introduced legislation to give climate change skeptics a place in the classroom.

The Green blog in the New York Times offers another scary statistic:

Dr. [Eugenie] Scott [head of NCSE] said national surveys of science teachers indicated that “one-third or more of their teachers have experienced some kind of push-back on the teaching of climate change.”

“Climate affects everyone, and the decisions we make today will affect generations to come,” says Scott in a press release. “We need to teach kids now about the realities of global warming and climate change, so that they’re prepared to make informed, intelligent decisions in the future.”

Image: The University of York/Kevin Hicks