I vividly recall the Ndebele villages I visited growing up in South Africa. Their colourful houses and intricate beadwork dazzled with artistic flair, but the enduring cultural image for me was the copper and brass rings that adorned the necks of Ndebele women. The rings (idzila) symbolised a wife’s loyalty and bond to her husband, while the actual number of rings depended on the husband’s riches. Wealthy husbands could provide their wives with more rings. Married women would only remove the rings after their husband’s death.

The Kayan (Padaung) tribe of Southeast Asia hold the record for the longest necks. From a young age, their women wear brass coils (instead of rings) around their necks, which can increase the distance between their collarbones and chins to 19.7 cm (7.75 in). Although we speak of long necks, the neck length does not change. It is an optical illusion. The appearance of a long neck is created by the coils pushing their chins up and their collarbones down. The deformed clavicles and compressed rib cages remain as permanent body modifications.

The Bajau people of Malaysia and the Philippines are famed freedivers. These “sea nomads” can plunge down to depths beyond 100m and hold their breath for 5 minutes at a time. Their impressive feats are not merely the result of cumulative training but are guided by the invisible hand of natural selection. Bajau individuals have abnormally large spleens, resulting from a genetic mutation that has enabled them to evolve for life at sea. The spleen is a reservoir of oxygen-rich red cells that are released into the circulation during oxygen deprivation. The larger spleens of Bajau divers give them a distinct advantage. Interestingly, the Bajau also share DNA fragments that can be traced back to the Denisovans, an extinct ancient hominid that interbred with early humans and Neanderthals. Denisovan genes allow modern Tibetans to survive at high altitudes. More amazing feats may become evident as scientists, working on gene editing, load our genetic dice. Like every doctor tells you: Your genetics load the gun. Your environment pulls the trigger.

I’ll be having breakfast at Denny’s this morning. When the name Denny is mentioned, it’s not a restaurant chain that I think about. No, it’s something far more interesting.

Tibetans live at altitudes that would make most humans ill. On the “roof of the world”, in the Qinghai-Tibetan Plateau, Tibetans thrive at dizzying heights with low levels of oxygen. Research has found genetic mutations that allow Tibetans to thrive at altitudes above 4000 meters, and … wait for it… they inherited those genes from an extinct human species!

The Denisovans were a mysterious subspecies of human that disappeared about 40,000 years ago. They co-existed and interbred with Neanderthals and early humans. The first ancient-human hybrid discovered was half Neanderthal and half Denisovan. She was nicknamed “Denny”. Denny’s mitochondrial DNA was sequenced from the tip of a finger bone found in Denisova Cave in the Altai Mountains of Russia.

Human interbreeding with the Denisovans transferred a gene called EPAS1 to humans. Known as the “super athlete” gene, EPAS1 regulates haemoglobin production when blood oxygen levels drop; improving oxygen transport throughout the body.

Denny’s Denisovan DNA has lived on in Tibet, allowing Tibetan descendants to acquire immunity against mountain sickness. Her species has helped humans adapt by acquiring traits through interbreeding. Unfortunately, we probably didn’t return the favour because the Denisovans became extinct soon after gifting their helpful DNA to us.

In honour of Denny’s finger and the genetic contribution Denisovans made to the human species, I feel like the Denny’s restaurant chain should change its slogan. Too bad “finger licking good” is already taken.

How did deaf people riding the waves in Nova Scotia contribute to space exploration?

During preparations for space travel in the late 1950s, there were several unanswered questions about the ability of human physiology to adapt to conditions in space. NASA recruited 11 deaf men (the “Gallaudet Eleven”) to study the effects of weightlessness and motion sickness on the human body. At early ages, these men had contracted spinal meningitis, which damaged their inner ears. They became deaf, but more importantly to scientists, their vestibular (balance) systems no longer functioned properly, making them immune to motion sickness. They underwent flights in the “Vomit Comet” aircraft and endured countless tests. When these men sailed the raging seas off the coast of Nova Scotia, the experiment had to be cancelled because researchers were overcome with sea sickness. The deaf test subjects, blissfully unaware, were playing cards and watching the stars bounce around in the sky.

Your anus developed before your mouth did. Humans are deuterostomes, and the name deuterostome means “mouth second”. This fact has sparked several thought experiments on the internet like: When two people kiss, they create a long tube from anus to anus. As for the musing that “your belly button is just your old mouth”, it doesn’t quite work that way.

Otonamaki (‘adult wrapping’) was inspired by ‘Ohinamaki’; the ancient Japanese practice of wrapping babies up in cloth to aid their physical development and provide feelings of security. The practice of Ohinamaki spread to include swaddling young mothers in the foetal position (Otonamaki), promising them relief from postpartum aches and pains. Anxious adults have since rebranded the cloth-cocoon as a relaxation strategy. I think a collection of human-filled cloth-cocoons hanging from the ceiling is probably less creepy than body suspension via flesh-piercing hooks. If I started an Otonamaki clinic, I would call it ‘The Panic Womb.’

What do sunken battleships have to do with medical scanners?

Whole-body counters and lung counters, which measure the amount of radiation in the human body, need to deliver accurate readings. They are also robust equipment, made of steel. Steel production, in turn, uses atmospheric air. When humans started detonating atomic bombs, radiation was released into the atmosphere, contaminating steel made after 1945 with radioactive particles. Medical radiation-measuring devices and Geiger counters need non-radioactive steel for accurate measurements.

The solution to the problem is to use low-background steel, or steel that was made before the first atomic bomb exploded. A supply of uncontaminated steel can be found at the bottom of the ocean. Water blocks radioactive energy, turning sunken battleships into an abundant source of uncontaminated steel. Steel is stripped from the underwater ships and recycled for use.

The most famous source of low-background steel is the scuttled German World War I battleships in Scapa Flow. The defeated German navy was forced to surrender its fleet at the end of the First World War. German ships were moved to Scapa Flow in the Orkneys until the Allies could decide their fate. Some Allied countries wanted the battleships for themselves while others, with already well-endowed naval forces, wanted them destroyed. But German Admiral Ludwig von Reuter was not about to let the Allied powers divide up the spoils of war. He gave the order to scuttle the entire German fleet at the Royal Navy’s base at Scapa Flow, in Scotland. Within 5 hours, 52 ships were scuttled. This is the greatest loss of shipping in a single day in history (the equivalent of about 400,000 tons of material).

Unwittingly, von Reuter’s act in 1919 paved the way to solve a post-1945 problem that the admiral could not have imagined in his wildest dreams.

Louis Braille, the inventor of the Braille system of written language for the blind, created his system using a similar tool he blinded himself with as a boy.

While playing in his father’s leather workshop at the age of three, Louis accidentally stabbed himself in his right eye with an awl. The injured eye was unsalvageable, and the trauma caused an inflammatory response (known as sympathetic ophthalmia) which caused blindness in his other eye too.

Braille learnt of a military communication devised by Captain Charles Barbier of the French Army. Barbier’s “night writing” consisted of a code of dots and dashes on thick paper. These impressions could be covertly read by the touch of a finger; allowing soldiers to communicate on the battlefield without needing to speak or have light.

The Captain’s system was too complicated, so Braille simplified it into a six-dot cell that can easily be read by passing one’s fingertips over an arrangement of embossed points.

At the time of his death, Louis Braille was working on a system of musical notation for the blind. Many blind people are musicians by profession and Braille, himself, was a gifted musician. He died, at 43 years of age, from tuberculosis.

TL;DR version: Louis Braille was blinded as a boy when using an awl. Also using an awl, he invented a reading system for the blind.