system
Given the following post, respond as if you're commenting on Reddit:
human
Do we have any way of knowing if early humans (ie Neanderthals, Homo Erectus) suffered from similar mental conditions, such as depression?
gpt
There's a strong social factor in depression, so the first question should be: did pre-historic/pre-agricultural Homo sapiens suffer from depression?

That said, there's been been quite a bit of research in chimps. Captive chimps frequently develop depression-like behavioral disorders

p.s. regarding the first point above: 

>A correlation between depression and modernization predicts a very low prevalence among hunter-gatherers. Community-based investigations of mental disorders using cross-culturally valid diagnostic tools among traditional populations are needed to assess this possibility. There is scant evidence that depression is rare among people living close to the human EEA, e.g. the Kaluli of New Guinea (Schieffelin, 1986), the Thai-Lao of Thailand (Keyes, 1986), and the Toraja of Indonesia (Hollan and Wellenkamp, 1994; Hollan and Wellenkamp, 1996). The rare case studies of depression reported by anthropologists should be interpreted with extreme caution since there was no systematic community sampling, nor formal diagnostic instruments used. Departure from a hunter-gatherer living is an opportune window for insight into the effects of modernization. The Ik of Uganda purportedly become more depressed upon shifting from hunter-gather to agricultural practices (Stevens and Price, 2000). After indigenous circumpolar peoples rapidly modernized, there was a rampant incidence of diabetes and suicide rates tripled within a decade (Shephard and Rode, 1996).  
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>Other lines of evidence suggest modernization is associated with depression. Indexing modernization by measures of belief in magic, hunting, gathering, agriculture, and technological complexity, a cross-cultural analysis of community women in rural Nigeria, urban Nigeria, rural Canada, and urban U.S. found the degree of modernization to correlate with a higher prevalence of depression in a dose-dependent manner (Colla et al., 2006). Adoption of the American lifestyle appears to explain higher rates of depression in Mexican Americans born in the U.S. compared to Mexican immigrants (Vega et al., 2004). As metropolitan China has undergone rapid cultural transformation over recent decades, the risk of suffering from depression appears to have risen dramatically: in a retrospective study, Chinese born after 1966 were calculated to be 22.4 times more likely to suffer from a depressive episode during their lifetime compared to those born earlier than 1937 (Lee et al., 2007). In developed countries, urban dwellers have a higher prevalence of psychiatric disorders, and specifically mood and anxiety disorders, compared to rural counterparts (Peen et al., 2010). British households rated as more traditional, e.g. church-going, have lower rates of depression (Brown and Prudo, 1981). In an investigation of affective disorder prevalence among the Amish, a community that maintains a traditional agrarian culture with notable unity and social connectedness, the prevalence of MDD was found to equal that of bipolar disorder- about 1% (Egeland and Hostetter, 1983). The above evidence suggests higher depression prevalence and risk is associated with general aspects of modernization.  
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>*(Hidaka BH. Depression as a disease of modernity: explanations for increasing prevalence. J Affect Disord. 2012;140(3):205–214. doi:10.1016/j.jad.2011.12.036)*