The sexual division of labour regarding house construction shows a very consistent pattern cross-culturally: women usually construct the shelters in nomadic societies, while in sedentary societies men do it.

This paper is a goldmine on scientific self-experimentation. -14 Nobel Prizes have gone to self-experimenters. - Of 465 scientific self-experiments documented over a 203-year period, there have been 8 deaths. - The most recent recorded death from a self-experiment was in 1928, when Alexander Bogdanov injected himself with an incompatible blood type. - Many universities say that self-experimentation would require IRB approval because it violates "ethical norms for medical research," which is not true; the Nuremberg Principles make an explicit exception for people experimenting on themselves, and the Declaration of Helsinki just says the subject must consent. Also, "there is no law nor regulation identified that requires investigators experimenting on themselves to consult an ethics committee." - There are lots of recent self-experiments; "In 2014, Philip Kennedy had electrodes implanted into his speech center to further his research on direct brain interfaces. In 2016, Alex Zhavoronkov self tested drugs which his software algorithms identified as likely candidates."

Lots of good tips in here on improving your reading and writing habits

My favorite paper this week: Human cells with damaged genomes (from cancer, radiation, or even CRISPR editing) grow tube-like bridges to their neighbors and send them broken chromosomes. The transferred DNA sticks around in the receiving cell and remains functional. This paper is really cool, and hints at *so many* interesting questions, but it’s important to caveat that it isn’t the first time people have seen DNA moving between human cells! There’s a 2013 paper (Jin Cai et al.) that shows extracellular vesicles (membrane-enclosed bubbles that bleb off cell membranes) can also carry DNA between cells. A similar thing happens with “apoptotic bodies.” Basically, when a cell dies, pieces of that cell will form into little spheres, some of which contain DNA. These “apoptotic bodies” are then engulfed by neighboring cells, which take up their DNA and (sometimes) incorporate the sequences into their own genomes. (See the Holmgren et al. paper from 1999.) People had even shown that nanotubes can swap DNA between cells! They hadn’t seen this with nuclear DNA, though; mostly mitochondrial DNA and various RNAs. This paper, then, is extremely original and exciting, yet sits within a rich subfield of cell-cell DNA transfers. The experiment was extremely simple. The researchers grew two types of human cells together in a dish. They tagged the histones in each cell type with a different fluorescent color; one green and the other red. Next, they exposed the cells to drugs that interfere with mitosis and recorded time-lapse videos. In one of these videos, they literally watched as DNA tagged with one color moved — through the thin nanotubes — into a cell with the other color. This happened not only with mitosis-blocking drugs, but also with CRISPR-induced chromosome breaks and radiation. The transferred DNA remained functional, too; they were transcribed into RNA and translated into protein. (Sidebar: It seems like this whole discovery was an accident. The group behind this paper had previously studied what happens to nuclear DNA when chromosomes break using exactly the same techniques and drugs. But it seems like they never expected to see this transfer happen between cells. They write in the paper: “Surprisingly, using live-cell imaging to monitor cytoplasmic DNA labeled with a double-stranded DNA-specific fluorescent dye, we observed the apparent transfer of DNA from the cytoplasm of donor cells to neighboring recipient cells.”) It’s not clear to me how important this might prove for, say, cancer. But the authors point at some intriguing ideas. Maybe the transfer of DNA between cells “mimics” some of the genome architectures we see in cancer cells, for example. Perhaps “DNA transfer could generate genomic alterations in recipient cells that resemble whole-chromosome gains or non-tandem duplications, challenging the assumption that these changes originate exclusively from cell-autonomous mitotic defects.” The researchers also speculate that DNA transfers could “potentially enable genomically unstable cancer cells to disseminate oncogenic alleles, deleterious mutations, and/or regulatory elements to neighboring non-cancerous cells.” If this turns out to be true, nanotubes could be a useful target for cancer therapies. Anyway, I love papers like this, where it feels like a whole swath of questions suddenly arises from beneath your feet. There is so much work to be done, and biology goes ever deeper.

This is a lot of fun to play with. Check it out!

You can give a kidney away but you can't sell it despite the fact it would save numerous lives. Insane.

Most of the natural world is invisible to us unless you watch carefully.

Could you help me collect data? It's a fun game that takes only a few minutes, but it will really help my colleagues and I to better understand human beauty preferences. Please share to help increase sample size; I'm grateful for your support for science.