 Why are there only 11 men on the planet's surface?
The robots were built to serve Man; to do his work, see to his comforts, make smooth his way. Frowning, worrying about the sounds, Alan momentarily forgot to watch his step until his foot suddenly plunged into an ant hill, throwing him to the jungle floor. At midday some few of the blue sun's rays filtered through to the jungle floor, but now, late afternoon on the planet, the shadows were long and gloomy. Then, through the trees he saw the clearing of the camp site, the temporary home for the scout ship and the eleven men who, with Alan, were the only humans on the jungle planet, Waiamea. Beyond, nose high, stood the silver scout ship that had brought the advance exploratory party of scientists and technicians to Waiamea three days before. Without pausing to think, Alan leaped back, and fell sprawling over a bush just as one of the robots rolled silently up from the right, lowering its blaster barrel to aim directly at his head. The robot started to shake, then clicked sharply as an overload relay snapped and shorted the blaster cells. If I can just hold out until morning, when the big ship arrives ... The metal killers, tuned to blast any living flesh, would murder them the instant they stepped from the ship! It was crazy, he supposed, to marry a girl and then take off for an unknown planet, with her to follow, to try to create a home in a jungle clearing.
 They served as a lookahead team for a larger group.
 They wanted to establish a colony only for men.  They served as a lookahead team for a larger group.  They wanted to go unnoticed as they set up on the planet's surface.  There was not enough space on the ship for more people.