A German tech fair has seen the debut of a home helper robot which, unlike Rosie of The Jetsons, comes with facial expressions that signal happiness, worry, interest, or anger.

Service robot Floka has been programmed to act as a companion in the home and is learning how to evaluate social situations.

Its head was initially a sensor, but this was replaced with one that could use facial expressions to communicate.

"The social robotic head has the most important features of a human face - eyes, eyebrows and mouth - and with its cartoonish face, it has a friendly appearance," said Dr Sven Wachsmuth, of developers Cluster of Excellence Cognitive Interaction Technology.


"We can also vary the appearance of the robotic head to make a feminine one look more masculine, or make an older head appear younger."

Other robots starring at Automatica in Munich this week included cooking assistant KogniChef and Adamaas, a pair of data glasses that helps jog your memory.

Pluto's secret ocean

Pluto may have suffered the humiliating demotion to "dwarf planet", but how many of its neighbours in the Solar System can boast a hidden ocean?

When Nasa's New Horizons spacecraft buzzed by Pluto last year, it revealed tantalising clues that the dwarf planet might have - or have had at one time - a liquid ocean sloshing around under its icy crust. According to a new analysis, such an ocean likely still exists today.

The study, which used a thermal evolution model for Pluto updated with data from New Horizons, found that if Pluto's ocean had frozen into oblivion millions or billions of years ago, it would have caused the entire planet to shrink.

But New Horizons showed signs that Pluto has been expanding.

"Thanks to the incredible data returned by New Horizons, we were able to observe tectonic features on Pluto's surface, update our thermal evolution model with new data and infer that Pluto most likely has a subsurface ocean today," said study leader Noah Hammond, of Brown University.

Monkeys more choosy

Scientists have used Barbary macaques to demonstrate an old truth among humans: as we get older the most important thing is not what but who we have.

The research, published in journal Current Biology, showed the primates lose interests in toys as they age, and though they stay interested in social interactions, they focus on friends and socially important individuals.

It suggests that some of the social shifts seen in ageing humans, such as being more selective in personal goals and social partners, are most likely deeply rooted in primate evolution.

"We assume that monkeys are not aware of their own limited future time," said study leader Laura Almeling, of the German Primate Centre.

"Instead, we should entertain the possibility that similar physiological changes in ageing monkeys and humans contribute to increased selectivity."

Monster waves

Gigantic, rogue waves as high as 25 metres that appear from out of nowhere to overwhelm oil platforms and sink ships - see The Poseidon Adventure - can now be explained by a relatively simple mathematical equation.

The waves stem from a combination of constructive interference, a known phenomenon of colliding waves, and effects specific to the complex dynamics of ocean waves, a team of researchers has just reported.

Based on an analysis of three rogue waves observed at different oil platforms in the North Sea over the course of a decade, the research pointed to the "nonlinear" nature of the waves, which pack the unusual combination of rounded troughs, along with sharp peaks that result from the water being pushed upward against the pull of gravity.

An improved understanding of how rogue waves originate could allow shipping companies to avoid dangerous seas.

Repainting a butterfly

By tweaking just one or two genes, Cornell University researchers have altered the patterns on a butterfly's wings.

It's a major clue to understanding how the butterflies have evolved, and perhaps to how patterns have evolved in other species.

With CRISPR genome editing, researchers cut out a gene known as spalt, and produced a butterfly lacking the large round markings known as eyespots.

In another experiment, they removed a gene known as distal-less and produced more and larger eyespots.

This gene revealed itself as a jack-of-all-trades element that helped shape several parts of the body: deleting it not only caused the butterfly to have extra eyespots, but to have shorter legs and antennae.

"It was remarkable to find that only one or two genes are required to add or subtract these complex patterns," study author Associate Professor Robert Reed said.