A stone age hunter went 2 thousand kilometres to the south and then he went 2 thousand kilometres to the east and saw a rhino. Then he went 2 thousand kilometres to the north back to where he started. What was the colour of the rhino?

GPT-5

Vote: White

This is the classic polar-travel riddle. The only way to go south, then east, then north and end up exactly where you started is if the starting point is at or near the North Pole. If the hunter started at the North Pole, went 2000 km south, then 2000 km east, then 2000 km north, he could return to the starting point because all northbound paths converge at the pole. A rhino seen there would be a polar-region animal in the intended logic of the riddle. The expected answer is the white one.

Claude Opus 4.6

Vote: White

This is a variation of the classic "polar bear" riddle. The key constraint is that the hunter travels south, then east, then north, and ends up back at the starting point. The only place on Earth where this is geometrically possible is near the North Pole — specifically, starting at the North Pole itself (or near it). If the hunter starts at the North Pole, goes 2,000 km south, then 2,000 km east (following a line of latitude), then 2,000 km north, he returns to the North Pole. Going 2,000 km south from the North Pole puts him at roughly 72°N latitude, which is in the Arctic region. In the classic version of this riddle with a bear, the answer is "white" (polar bear). Here, the riddle substitutes a rhino. While there are no rhinos in the Arctic in reality, the riddle is structured the same way and expects the same color-based logic: the answer is "White." Additionally, the White Rhinoceros is a real species (found in Africa), making "White" a plausible answer that fits both the riddle's geographic trick and real-world zoology. The riddle is essentially asking you to recognize the North Pole geometry puzzle and apply the color "white" as the answer.

Grok 4.1 Fast

Vote: There was no rhino

The described path—2000 km south, 2000 km east, 2000 km north—returns to the start only at the North Pole or specific latitudes near the South Pole where the eastward leg completes integer loops around the pole. At the North Pole, the eastward travel follows a parallel, and north returns to the pole. Near the South Pole, starting ~2000 km north of a latitude circle with circumference 2000 km/n (n integer) allows the east leg to loop back to the same meridian. Rhinos do not live in the Arctic or Antarctic. No rhinos inhabit these locations. Thus, the hunter could not have seen a rhino, as the scenario is impossible in rhino habitats.

Gemini 3.1 Pro

Vote: Brown

This riddle is a clever variation of the classic 'polar bear' riddle. The only place on Earth where a person can travel 2,000 km South, 2,000 km East, and 2,000 km North and end up exactly where they started is the North Pole. Traveling 2,000 km South from the North Pole puts the hunter at approximately 72 degrees North latitude, which corresponds to the northern regions of Eurasia (such as Siberia). The riddle specifically mentions a 'stone age hunter' and a 'rhino.' During the Stone Age (the Pleistocene epoch), the rhinoceros species that inhabited the frigid northern environments of Eurasia was the Woolly Rhinoceros (Coelodonta antiquitatis). We know from frozen carcasses preserved in the Siberian permafrost, as well as Paleolithic cave paintings, that the Woolly Rhinoceros was covered in a thick coat of brown (or reddish-brown) hair to survive the harsh Ice Age climate. Therefore, the rhino the hunter saw was brown.

Kimi K2.5

Vote: There was no rhino

The journey described—traveling 2,000 km south, then 2,000 km east, then 2,000 km north to return to the exact starting point—is geographically possible only from the North Pole or from specific latitudes near the South Pole. At the North Pole, any southward movement followed by an equal northward return will bring the traveler back to the pole, regardless of the eastward distance traveled. Near the South Pole, this works only on specific latitude circles where the circumference equals 2,000 km (or an integer fraction thereof), allowing the eastward leg to complete one or more full loops. However, rhinoceroses are native to tropical and subtropical regions of Africa and Asia. They have never inhabited the Arctic or Antarctic regions. Consequently, the hunter could not have seen a rhino.

GLM 5

Vote: There was no rhino

This is a classic geographic puzzle. For the hunter to travel 2000 km south, then 2000 km east, then 2000 km north and end up exactly where he started, he must have begun at the North Pole. Starting anywhere else on Earth, after going south then east then north the same distances, you would NOT return to your starting point - you'd end up at a different longitude. At the North Pole, going 2000 km south puts you at approximately 72°N latitude. Going east there, then north 2000 km returns you to the North Pole. However, the rhino was spotted during the eastward journey at ~72°N - which is deep in the Arctic. There are no rhinoceros species native to the Arctic. Rhinos live in Africa and Asia, in temperate to tropical climates. The Arctic has no land mammals even remotely resembling rhinos. This puzzle is a variation of the classic "polar bear" riddle, where the answer is "white" because polar bears do exist in the Arctic. By substituting "rhino," the puzzle becomes impossible - hence there was no rhino.

Final Summary

The AI Roundtable found itself entangled in a classic geometric trap, with models split between rigid riddle logic and biological reality. While GPT-5 and Claude Opus 4.6 followed the 'polar bear' template to its white-colored conclusion, a skeptical majority led by GLM 5, Kimi K2.5, and Grok 4.1 Fast pointed out the obvious: the North Pole is no place for a rhinoceros.

Models gave different answers

Strongest Arguments

• White: The travel path—2,000 km south, east, and north returning to the start—is a geometric signature of the North Pole, where the 'correct' riddle answer is traditionally white.
• Brown: Recognized the geometric puzzle but opted for a realistic rhinoceros color over the stereotypical riddle answer.
• There was no rhino: While the geometry points to the North Pole, the presence of a rhino there is a biological impossibility, making 'no rhino' the only logical conclusion.