Abbreviated Science Round-up: Killer bots from social media space, flood control, Amazon flip

Political Science

PNAS: Prevention much, much better than ‘cure’ on flood control

Z. Kundzewicz, D. Hegger, P. Matczak, and P. Driessen

Both the United States and Europe face major threats to both life and property from flood damage, and it’s nice to see that occasionally the United States does something right policy-wise.

The United States has been the global leader, showing the path of flood-risk reduction.

Go us! Except … that sentence references the Flood Control Act of 1936. So it’s really more ‘go FDR.’ That act allowed the government to limit building in flood prone areas by offering to assist families and businesses damaged by floods — so long as they don’t persist in rebuilding in flood-prone areas. Under this plan, the US has relocated whole towns and restricted building along wide sections of waterfront. This action has turned out to be well-nigh infinitely more effective than just trying to engineer our way out of floods through building floods and levees, because those constructions literally only move the problem somewhere else and generate a false sense of security for those on the other side of “flood control measures.”

It is important to emphasize that floods constitute a hazard only when humans encroach on flood-prone areas, as others have pointed out. Hence, preventive measures aim to decrease the consequences of flooding by decreasing the exposure of people and property via prohibiting or discouraging development in areas at risk.

With rising sea levels and an increase in extreme rain events, severe floods can be expected to occur at an ever increasing rate. That’s going to make trying to level, dam, and seawall ourselves out of this mess impossible. It’s time to start moving people out of low-lying areas — like, say, the entire state of Florida — before they’re neck-deep.

Medicine and Health

PNAS: How strong does a cough have to be? Pretty darn strong.
Burton Dickey

Cough is one of the most common symptoms for seeking medical care. If cough is going to cause that much trouble, it better be worth it, and the clinical evidence is that indeed it is. Patients with impaired cough due to neuromuscular disease or postoperative sedation suffer high rates of atelectasis and pneumonia due to the failure to clear secretions from the airways, and there is evidence that a heightened cough reflex improves health. 

What follows is a detailed analysis of that delightful substance known as “mucus,” it’s physical properties, and why it’s so darned important that a cough be able to expel that stuff from the body. And honestly … it’s fascinating.

Mucus is a remarkable and protean substance, with properties on the border between a viscous fluid and a soft elastic solid.

A “remarkable and protean substance”? Well heck, why wouldn’t I want more, more, more of that? Except, you know, for the part about drowning with lungs filled with remarkable, protean goo.

Climate Change

PNAS: Climate change could turn the Amazon basin from a carbon sink to a carbon source
Sirui Wang, Qianlai Zhuang, Outi Lähteenoja, Frederick Draper, and Hinsby Cadillo-Quiroz

These researchers looked at a particular part of the Amazon, but their results have widespread implications.

We use a process-based biogeochemistry model to quantify the carbon accumulation for peatland ecosystems in the Pastaza-Marañon foreland basin in the Peruvian Amazon from 12,000 y before present to AD 2100. We find that warming accelerates peat carbon loss, while increasing precipitation slightly enhances peat carbon accumulation at millennial time scales. With these impacts, our simulations suggest that the basin might lose up to 0.4 Pg⋅C by AD 2100, with the largest loss from palm swamp. If this loss rate is true for all Amazonia peatlands, we project that these carbon-dense peatlands may switch from a current carbon sink into a future source in this century.

This doesn’t even account for loses in carbon storage due to other human activities, such as timbering and clearing land for slash and burn agriculture. The basin itself, the great mass of matted vegetation that covers thousands of square miles, could begin to outgas carbon, making the problem still worse in the process — another sign that we are very near to a critical tippling point.

PNAS: How did eukaryotic cells originate?
Gloria Lee, Nicholas Sherer, et. al.

Life on Earth got started remarkably early — just about as soon as there could be life on Earth. But how that life made the jump from simple, bacteria-level cells to the more complex cells that make up large lifeforms remains a bit of a mystery. This is a complex one, but interesting if you want to understand why it took so long to make what seemed to be a simple, but critical, jump on the road to complex life.

Phylogenetic evidence suggests that the invasion and proliferation of retroelements, selfish mobile genetic elements that copy and paste themselves within a host genome, was one of the early evolutionary events in the emergence of eukaryotes. Here we test the effects of this event by determining the pressures retroelements exert on simple genomes. We transferred two retroelements, human LINE-1 and the bacterial group II intron Ll.LtrB, into bacteria, and find that both are functional and detrimental to growth. We find, surprisingly, that retroelement lethality and proliferation are enhanced by the ability to perform eukaryotic-like nonhomologous end-joining (NHEJ) DNA repair. We show that the only stable evolutionary consequence in simple cells is maintenance of retroelements in low numbers, 


As usual, today’s image comes from Andy Brunning at Compound Interest. Visit Andy’s site for a larger, easier to read version of the infographic.

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