Welcome to this week’s Sunday Science, featuring a successful immunotherapy trial for advanced melanoma, sensitive prosthetic limbs, Bronze age baby bottles, an intriguing study of genetic adaptation in whales and dolphins, dreaming octopuses and one incredibly tough little worm…

A new treatment regime can extend the lifespan of patients with advanced melanoma significantly, with half living for five years or more after treatment. Melanoma, a highly invasive skin cancer, is relatively easy to treat if it’s caught before it spreads. However, in many cases, it isn’t detected this early, and then the prognosis has been dismal – less than 10% survival if it’s spread to distant sites, and with a median survival of less than a year. The new treatment combines two immuntherapy drugs, ipilimumab and nivolumab, which are antibodies that target cancerous cells. This adds to a growing body of evidence of the significant effectiveness of immunotherapy drugs, which generally also have less severe side effects than chemotherapy or radiotherapy. Trial results published in the New England Journal of Medicine here (paywalled).

Feeding babies animal milk from bottles is not a modern phenomenon: ancient baby feeding cups with trace residues of milk have been found in Bronze Age graves in Bavaria, and are around 3000 years old (featured image). It’s an important find, and may help explain why there was a population boom around this time – if infants could be weaned off breastmilk a bit earlier and onto a reliable source of animal protein, it could help share childcare around communities that were adopting settled farming lifestyles. Additionally, it may have reduced the birth interval between siblings (babies can start to be weaned off breastmilk from around 6 months; the natural age timing of complete cessation of breastfeeding varies from around 2-7 years of age). A number of the vessels seemed to have doubled as toys, and are very charming, but it’s also rather sad – they were recovered from children’s graves, aged between 1-6 years old. Infant mortality at that time would have been extremely high, and it is true that earlier exposure to non-human milk sources in non-sterile containers could have increased the risk of infection. A Nature News and Views opinion piece is here, with the original study published here (paywalled).

One of the major drawbacks of prosthetic limbs, as I’ve noted before, is the lack of sensory feedback from the artificial limb – which our bodies rely on to navigate successfully through the world. Now scientists have developed bionic legs that allow amputees to sense feedback from the leg, allowing them to navigate around and over obstacles without having to watch what the legs are doing. The limbs have sensors that generate information about touch and movement on the limb, which are converted to signals that feed directly into nerves in the stump of the amputated limb. Moreover, less mental effort in general is required to operate the limb, and the subjects reported that it felt like it was properly part of their bodies, overcoming a psychological barrier to artificial limbs as well. Original study in Science Translational Medicine reported here (paywalled).

During the transition from land to water, cetaceans (whales and dolphins) would have undergone many evolutionary changes. Many studies have looked at genes that were positively selected for or evolved de novo during this transition. An interesting study has now looked at some of the genes that were instead lost (inactivated) during this process, finding 85 genes. There are many interesting finds: for example, the loss of some genes would have reduced the risk of dangerous blood clots forming during deep diving, and enhanced lung function for the same reason. Less obviously, one gene loss indicates a reduced need to make saliva, and at least three, involved in the synthesis and signalling process of melatonin, the sleep hormone, may help explain the evolution of unihemispheric sleep (the animal sleeps with only half of its brain actually asleep at any one time). Original study published in Science Advances here (open access).

A new species of microscopic worm has been discovered that lives in a highly salty, alkaline lake in California. The conditions in the lake are really inhospitable for most forms of life, but this tough little nematode not only lives there, but can survive 500 times the lethal human dose of arsenic. The worm can justifiably be classed as an extremophile – an organism that can survive in unusual environments that are too hostile for most life on Earth. Most of these are single-celled organisms; it’s rare to find a multicellular animal that can thrive in such harsh conditions. Interestingly, it’s arsenic tolerance is a common feature of the Auanema genus to which this nematode belongs, suggesting that many of these worms are adapted to live in these types of environments. Original study published in Current Biology here.

And finally, an intriguing and rather beautiful video of an octopus changing colours as it sleeps – and, probably, dreams.

Featured image

Two vessels of the type found in Bronze Age graves from Austria contain animal milk residues, and are likely to have been used to feed infants. From Dunne et al, 2019, via Nature Publishing. https://doi.org/10.1038/s41586-019-1572-x.

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