While it's possible that early humans may have occasionally used hot springs to cook their food, there is no direct evidence to suggest that they consistently relied on this method. Cooking food in hot springs would require the availability of suitable natural hot springs, and it's not clear how common these were in the environments inhabited by early humans.

Early hominins, like Homo habilis, were known to use fire for cooking around 1.8 million years ago. They probably used simple hearths or pits filled with hot coals to roast or grill meat and vegetables. As humans evolved and spread across different regions, they developed a variety of cooking methods and utensils, including pottery and ovens, which allowed them to cook food more efficiently and consistently.

Therefore, while it's an intriguing possibility, the idea of early ancestors routinely boiling their food in hot springs remains speculative and lacks substantial evidence.