LONDON—Wall Street headed for a lower start on Friday as investors sought to interpret a ‘mixed bag’ of payrolls numbers before the final session of a rollercoaster first trading week of the year. U.S. employment rose by a less-than-expected 199,000 jobs last month as the impact of a resurgent pandemic bites, well below the 400,000 forecast by economists, but data for November was revised higher. The unemployment rate dropped to underscore tightening labor market conditions. S&P 500 e-mini stock futures and Nasdaq futures, which had been firmer ahead of the data, turned weaker, pulling European shares towards their low for the day as investors studied the payrolls data for clues to the pace of anticipated interest Federal Reserve rates hikes. After a start to 2022 marked by new highs, the mood changed on Wednesday after minutes from the Fed’s December meeting signaled the central bank may have to raise interest …