The traits that helped Neandertals adapt to life in relatively cold climates are:
1. Increase in limb proportions: Neandertals had shorter limbs compared to modern humans, which helped them retain heat more efficiently in cold climates. Shorter limbs reduce the surface area through which heat can escape, making it easier for them to regulate their body temperature.
2. Increase in brain size: Neandertals had larger brains than modern humans, which could have provided them with better cognitive abilities to adapt to the challenges of living in cold climates. A larger brain size may have helped them develop more complex tools, strategies for hunting, and social interactions necessary for survival in harsh environments.
These traits combined helped Neandertals thrive in colder environments by enabling them to conserve heat, process information effectively, and develop advanced survival skills suited for their surroundings.