Some children suffer from completely tangled hair, which, as their parents will attest, can't be combed at all.
In German, the phenomenon bears the apt name "uncombable hair syndrome" or even "Struwwelpeter syndrome."
Now, researchers have identified mutations in three genes responsible - a finding that could pave the way for an actual clinical diagnosis of uncombable hair.
Two - named PADI3 and TGM3 - contain the assembly instructions for enzymes, while the third, TCHH, carries an important protein for the hair shaft.
In healthy hair, the TCHH proteins are joined to each other with extremely fine strands of keratin, which are responsible for the shape and structure of the hair.
During this process, the two other identified genes play an important role - PADI3 changes the hair shaft protein TCHH in such a way that the keratin filaments can adhere to it, and the TGM3 enzyme then produces the actual link.
The international team of scientists behind the new study, just published in the American Journal of Human Genetics, say a huge amount could be learned about the newfound mechanisms involved in forming healthy hair, and why disorders sometimes occur.
A city's DNA can be found on its ATMs
Here's something to think about next time you go to get cash out: your local ATM is a virtual repository of your community's DNA.
A new study has found automated teller machine keypads in New York City hold microbes from human skin, household surfaces and traces of food.
"Our results suggest that ATM keypads integrate microbes from different sources, including the human microbiome, foods, and potentially novel environmental organisms adapted to air or surfaces," explained study leader Professor Jane Carlton, of New York University.
"DNA obtained from ATM keypads may therefore provide a record of both human behaviour and environmental sources of microbes."
In the study, scientists took swabs of keypads from 66 ATM machines in eight neighbourhoods across Manhattan, Queens, and Brooklyn - and later used sequencing methods to reveal an array of human skin microbes.
Specifically, the most common identified sources of microbes on the keypads were household surfaces such as televisions, toilets, kitchens and pillows.
Researchers also found microbes from bony fish, molluscs, and chicken in different New York City neighbourhoods, suggesting that residual DNA from a meal may remain on a person's hands and be transferred to the ATM keypad upon use while also pointing to a link between geography and specific microbes.
Pokemon Go for conservation?
Since its launch in July, Pokemon Go has become a global phenomenon, reaching 500 million downloads within two months of release.
The augmented reality game, designed for mobile devices, allows users to capture, battle and train virtual creatures called Pokemon that appear on screen as if part of the real-world environment.
But can the game's enormous success deliver any lessons to the fields of natural history and conservation?
A new study explores whether its success in getting people out of their homes and interacting with virtual animals could be replicated to redress what is often perceived as a decline in interest in the natural world among the general public.
Its international authors say there's clear potential to modify the game itself to "increase conservation content and impact" above and beyond simply bringing gamers into "closer physical proximity" to wildlife as a byproduct.
It could be adapted to enhance conservation benefits by making Pokemon biology and ecology more realistic, adding real species to the Pokemon Go universe to introduce those species to a huge number of users and creating opportunities to raise awareness about them.
Further, they wrote, deliberately placing Pokemon in more remote natural settings rather than urban areas could draw people to experience nature.
Why are we ticklish?
Of all physical sensations, ticklishness is perhaps the most mysterious.
Why do we laugh in response to tickling?
Why are certain body parts more ticklish?
Why can we not tickle ourselves?
Scientists have investigated tickling in rats, building on earlier work that had shown that young rats respond with 50kHz ultrasonic "laughter-calls" to tickling by humans.
In the novel study, rats also reacted enthusiastically to the tickling - particularly when ticked on the belly and underneath their feet - and emitted numerous calls.
The researchers then went on to investigate the response of the rat's brain - specifically the somatosensory cortex, a large brain structure that contains an ordered representation of the body and handles stimuli on the body.
In the trunk region of the somatosensory cortex, the researchers observed nerve cells that responded strongly to tickling.
Interestingly, they found very similar brain responses during play behaviours as during tickling, even though the rats were not touched by the scientist.
Making rats anxious - which reduces ticklishness - also reduced the activity in these cells and suppressed the calls.
Remarkably, rats emitted calls just to electric stimulation of the cells in the trunk region of the somatosensory cortex without being tickled.
Taken together, these results suggest that activity in the trunk somatosensory cortex represented ticklish sensation.