Using machine learning, a computer model can teach itself to smell in just a few minutes. When it does, researchers have found, it builds a neural network that closely mimics the olfactory circuits that animal brains use to process odors. Animals from fruit flies to humans all use essentially the same strategy to process olfactory information in the brain. But neuroscientists who trained an artificial neural network to take on a simple odor classification task were surprised to see it replicate biology's strategy so faithfully. "The algorithm we use has no resemblance to the actual process of evolution," says Guangyu Robert Yang, an associate investigator at MIT's McGovern Institute for Brain Research, who led the work as a postdoc at Columbia University. The similarities between the artificial and biological systems suggest that the brain's olfactory network is optimally suited to its task.

Using machine learning, a computer model can teach itself to smell in just a few minutes. When it does, researchers have found, it builds a neural network that closely mimics the olfactory circuits that animal brains use to process odors. Animals from fruit flies to humans all use essentially the same strategy to process olfactory information in the brain. But neuroscientists who trained an artificial neural network to take on a simple odor classification task were surprised to see it replicate biology's strategy so faithfully. "The algorithm we use has no resemblance to the actual process of evolution," says Guangyu Robert Yang, an associate investigator at MIT's McGovern Institute, who led the work as a postdoctoral fellow at Columbia University. The similarities between the artificial and biological systems suggest that the brain's olfactory network is optimally suited to its task.

A joint project between Google scientists and researchers from Janella Research Campus in Virginia has created a high resolution 3D map of the fruit fly brain, the most detailed 3D model of a brain yet created. While fruit flies have tiny brains, roughly the size of a poppy seed, they behave in ways that indicate substantial intelligence. These behaviors include complex courtship dances and a tendency to investigate for hazards like toxic chemicals before choosing to move to new locations. In total, the fruit fly brain as around 100,000 neurons, about the same amount as a lobster, but less than a cockroach, which has around a million. Researchers had previously created a computer model of the fruit fly brain by analyzing a series of microscopic images, but this is the first time a map has been built from real 3D data.

Researchers have identified an incredibly smart method used by fruit flies to categorise odours – and it's so clever it could be applied to powering recommendation algorithms for the likes of Netflix or Spotify. In the same way that YouTube might want to flag up videos similar to the one you've just watched, fruit flies – like many other animals – need to know which smells are similar, for finding food and avoiding poisonous substances. The team from the University of California San Diego (UCSD) and the Salk Institute for Biological Studies in California has found that fruit flies have an especially clever way of categorising odours which lets them recognise differences with a very fine level of accuracy. "In the natural world, you're not going to encounter exactly the same odour every time; there's going to be some noise and fluctuation," says one of the researchers, Saket Navlakha from Salk. "But if you smell something that you've previously associated with a behaviour, you need to be able to identify that similarity and recall that behaviour."

What do a fruit fly and a search engine have in common? Search engine algorithms go through great pains to match items you've clicked on or purchased, songs you've listened to, or things searched for, to similar ones. As a result, we constantly need ever faster and more efficient search engines, and so computer scientists must work tirelessly to keep up. They have to constantly tackle what they call "a fundamental machine learning problem: approximate similarity (or nearest-neighbors) search." Turns out, fruit fly brains go through a similar matching process, and the way they do it is fast, efficient, and dare I say, elegant.

Ask, and it shall be given you; seek, and ye shall find; knock, and it shall be opened unto you." Verse 7:7 from the Gospel of Matthew is generally considered to be a comment on prayer, but it could just as well be about the power of search. Search has become one of the key technologies of the information age, powering industry behemoths and helping us with our daily chores. But that's not where it ends. Scientists are starting to understand that search powers much of the natural world, too. Saket Navlakha, of the Salk Institute for Biological Studies, works at the "interface of theoretical computer science, machine learning, and systems biology," a field, he told me, that he and his colleagues are calling "algorithms in nature." Evolution needs algorithms just as software engineers do, Navlakha says, because it "has also had to deal with building efficient, reliable, low-cost systems that help animals and organisms survive." His hope is to find in nature "new ideas and new engineering principles" that can be exploited by human scientists and engineers. In a study published on Friday, Navlakha and a couple colleagues, Sanjoy Dasgupta and Charles F. Stevens, did just that. They found that the fruit fly brain had some valuable lessons for anyone developing similarity search algorithms. Stevens had been studying fly neural circuits, specifically how they associate different behaviors, like approach or avoidance, with odors in the environment. "When he started telling me about it," Navlakha says, "I realized that what the fly needs to do is do something like a similarity search.

Examples of eight fruit fly brains with regions highlighted that are significantly correlated with (clockwise from top left) walking, stopping, increased jumping, increased female chasing, increased wing angle, increased wing grooming, increased wing extension, and backing up. Can you imagine watching 20,000 videos, 16 minutes apiece, of fruit flies walking, grooming, and chasing mates? Fortunately, you don't have to, because scientists have designed a computer program that can do it faster. Aided by artificial intelligence, researchers have made 100 billion annotations of behavior from 400,000 flies to create a collection of maps linking fly mannerisms to their corresponding brain regions. Experts say the work is a significant step toward understanding how both simple and complex behaviors can be tied to specific circuits in the brain.