This is scientific American's 60 second science. I'm Christopher Intalyata. Got a minute?

By the end of this century, the United Nations reckons the population of Africa could hit 4.3 billion people, four times today's numbers.

It's the fastest growing spot on the planet, which inevitably means growing pains.

We're seeing a real rush, almost a feeding frenzy of development activity with foreign mining

investment, in some cases land grabs.

Bill Lawrence, an ecologist at James Cook University in Australia.

We're living in the most active era of infrastructure and road

expansion in human history.

We're projected to see 25 million kilometers

of new paved roads on the planet by the middle part of the century, which is enough to go around the world more than 600 times.

33 of those roads, spanning 53,000 kilometers, are already planned in Africa.

So Lawrence and his colleagues examine the pros and cons of the new projects.

They measured potential benefits, like increased agricultural opportunities, and weighed those gains against environmental impacts.

The research team determined that the planned roads and railways would slice through more than 400 protected areas. And if you add on a 25

kilometer buffer zone on each side of the road, where Lawrence says new hunting,

poaching, farming, logging, and mining are bound to pop up,

the tally of violated protected areas rises logging and mining are bound to pop up,

Natalia violated protected areas rises to more than 2,000.

The researchers do endorse five of the 33 roads as promising.

Good for humans, not so bad for the environment. And they identify

the six worst-planned roads, which they say probably should not be built at all.

The study is in the journal Current Biology.

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