HUMANS of the future could have enormous lungs to live in underwater kingdoms, or biohacked brains where memories can be bought and sold for a fee.

That's according to two experts in pushing the human body to its limits discussing what "humans 2.0" will look like.

Speaking at Lisbon's Web Summit on Tuesday, Kernel founder Bryan Johnson said unlocking the potential of our brains is the "single greatest thing" humanity can strive for.

The former door-to-door salesman who founded payment company Braintree and sold it to eBay in 2013 for $800 million has now invested $100 million of his own cash in Kernel, an LA based start-up making microchips inserted in brains to read and write neural code. The plan is to use them to fight disease first before progressing to unlocking human superpowers.

"I would expect in around 15-20 years we will have a sufficiently robust set of tools for the brain that we could pose any question we wanted. For example, could I have a perfect memory? Could I delete my memories? Could I increase my rate of learning, could I have brain to brain communication?" he told the audience.

"Imagine a scenario where I say 'I want to know what it's like to be a cowboy in the American west in the 1800s' and someone creates that experience mentally. I'm able to take that and purchase that from that person and experience that."

Westworld fantasies aside, asked whether such technology could further divide the world into haves and have-nots, the man who suffered a decade of suicidal depression and had a drug-addicted father said he expects the technology will become "democratised, like smartphones."

"The bigger question on this is: 'Is working on this a luxury or a necessity," he said. "I don't understand what we are so scared of losing?

"I don't know why it would not be the singular focus of the human race because everything we do stems from our brain.

Blue Abyss' Space Operations Director Simon Evetts, who has supervised studies on the effect of space travel on astronauts, said the prospect of "directed evolution" raises questions about how the body could be adapted to live in currently hostile environments.

"Are we going to see an aspect of society moving into the oceans in future? And if they do so, what will they do to optimise themselves?

"Can we somehow work out how dolphins and seals hold their breath for so long and maybe ourselves do that? Are we going to try and internalise those things and end up with large thoracic cavities because we've got internal gill sets?"